Digital scale with means to shift displayed weight to show fraction of least normally displayed graduation

ABSTRACT

An improved electronic apparatus for accurately weighing, computing a value and printing a label showing the weight, the price per unit weight and the computed value of each of a plurality of successive articles. The scale generates a predetermined number of significant weight digits which are used in computing values and at least one additional least significant weight digit. A digital indicator is provided for normally displaying the significant digits of the corrected net article weight obtained from the measured gross article weight less the zero correction factor and any tare weight. The displayed weight may be shifted and the correcting of errors inhibited to permit displaying the additional least significant weight digit while checking or manually aligning the zero of the uncorrected scale output.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This is a continuation-in-part of my copending application Ser. No.434,431, filed Jan. 18, 1974 and now abandoned.

This application discloses features claimed in and also claims featuresdisclosed in the following copending patent applications: theapplication of R. C. Loshbough, Ser. No. 573,242 filed Apr. 30, 1975 for"Motion Detecting Scale" which is a continuation-in-part of the priorfiled application Ser. No. 434,384 filed Jan. 18, 1974; the applicationof R. C. Loshbough et al Ser. No. 573,149 filed Apr. 30, 1975 for"Digital Weight Measuring and Computing Apparatus With Automatic ZeroCorrection" which is a continuation-in-part of the prior filedapplication Ser. No. 466,303 filed May 2, 1974 which application in turnis a continuation of the application Ser. No. 434,400 filed Jan. 18,1974; the application of R. C. Loshbough et al Ser. No. 573,147 filedApr. 30, 1975 for "Value Computing Scale" which application is acontinuation-in-part of the prior filed application Ser. No. 434,401filed Jan. 18, 1974; the application of G. D. Robaszkiewicz Ser. No.573,141 filed Apr. 30, 1975 for "Apparatus for Isolating Errors inPrinted Records" which application is a continuation-in-part of theprior filed application Ser. No. 434,417 filed Jan. 18, 1974; theapplication of R. C. Loshbough et al Ser. No. 573,150 filed Apr. 30,1975 for "Scale with Manual Tare Entry" which application is acontinuation-in-part of the prior file application Ser. No. 434,663filed Jan. 18, 1974; and the application of G. D. Robaszkiewicz Ser. No.573,146 filed Apr. 30, 1975 for "Clear and Restart Arrangement forDigital Measuring Apparatus" which application is a continuation-in-partof the prior filed application Ser. No. 434,840 filed Jan. 18, 1974.

BACKGROUND OF THE INVENTION

This invention relates to weight measuring and value computing apparatusand more particularly to improved apparatus for weighing, computing avalue and printing an article label showing the weight, price per unitweight and computed value of each of a plurality of successive articles.Apparatus is provided for indicating centering of the indicated zerowithin a fraction of the least significant indicated weight incrementwhile the scale is empty.

In recent years the demand for increased efficiency has created the needfor high speed measuring apparatus capable of automatically weighingsuccessive articles and, for each weighed article, computing a valuebased upon a predetermined price per unit weight and printing an articlelabel bearing such weight, price per unit weight and computed value.Such measuring apparatus is commonly used, for example, in supermarketmeat departments. After a butcher cuts and divides meat into packageportions, the meat may be automatically packaged and subsequentlylabeled by automatic weight measuring, value computing and labelprinting apparatus.

In the past, apparatus for weighing an article, computing an articleprice and printing an article label have included a combination ofmechanical, optical and electrical elements. A typical prior art systemof this type is described in U.S. Pat. No. 3,384,193 which issued on May21, 1968 to William C. Susor et al and U.S. Pat. No. 3,453,422 whichissued on July 1, 1969 to William C. Susor. This system includes amechanical-optical scale which generates a digital signal correspondingto an article weight. A computer multiplies the measured weight by aprice per unit weight, using a partial products method ofmultiplication, to obtain the article's value. The measured weight data,the price data and the computed value data are then supplied to aprinter for producing an article label.

Although systems of this type have been extremely successful, there hasbeen a need for faster-operating and more accurate systems. Entirelyelectronic scale systems using load cells for generating analog weightsignals have been developed to meet these needs. The analog weightsignal is digitized and the digitized weight is displayed on a digitalindicator and supplied to a value computer. Electronic scale systems ofthis type must be manually checked and set to zero while no article ispresent on the scale platform. The zero setting must be checked andreadjusted periodically because of long term drift caused, for example,by temperature changes and component ageing. However, prior art systemsof this type have not permitted accurate determination and adjustment ofthe scale zero because the displayed weight is rounded off to thenearest digit. Even though the weight indicator displays a weight ofzero, the scale system may be on the verge of changing to plus or minusone since there has been no means for centering the scale output withinthe zero increment.

SUMMARY OF THE INVENTION

In accordance with the present invention, improved apparatus is providedto facilitate manually zeroing the scale including the electronicapparatus which is provided for successively measuring the weight ofarticles to be labeled, for computing an article value from eachmeasured weight and a price per unit weight supplied to the apparatus,and, for each weighed article, for printing a label bearing the measuredweight, the computed value and the price per unit weight used forcomputing such value. The apparatus is capable of operating at a highspeed with a high degree of accuracy in the measured weight and thecomputed value. A predetermined number of significant weight digits aregenerated by the scale for use in computing an article value and fordisplay. In addition, the scale generates at least one additional weightdigit of a lesser significance for use in automatic and manualcorrection of zero errors. The additional weight digit is a fraction ofthe smallest significant weight digit.

According to the present invention, the manual actuation of a switchdisables circuitry in the microcomputer which automatically zeros thescale output and also causes the weight digits appearing on the digitaldisplay to be shifted such that the additional weight digit and only aportion of the significant weight digits are indicated. One or more ofthe most significant ones of the weight digits are not displayed.However, these weight digits will be zero even when the scale outputdeviates from zero by a considerable amount. While the switch isactuated to shift the displayed weight, the scale is calibrated tocenter the output on zero to within a small fraction of the smallestsignificant weight digit. When the apparatus is thereafter returned to anormal operating and display mode of operation, small deviations fromzero in the scale output caused, for example, by a long term outputdrift resulting from component ageing, by temperature changes and bywander in the load cell output, are compensated for automatically.

The accuracy of the scale zero will be appreciated from the followingexample. If the displayed weight is indicated to two decimal places orto one one-hundredth of a pound, then the display will show zero weightfor actual weights ranging from -0.005 to +0.0049 pound. This is becausethe displayed weight must be rounded off to the nearest digit. Byshifting the displayed weight by only one decimal place and readjustingthe displayed weight to zero, the scale will be centered such that theactual deviation from zero is limited to the range of from -0.0005 to+0.00049 pound. This highly accurate zero setting is maintained afterthe displayed weight is shifted back to the normal display mode.Thereafter, any zero wander or drift will be compensated forautomatically in the microcomputer through the use of a zero errorcorrection factor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of apparatus embodying theprinciples of the present invention for weighing, computing a value andprinting a label showing the weight, price per unit weight and computedvalue of each of a plurality of successive articles;

FIG. 2, composed of FIGS. 2A - 2J, shows a flow diagram illustrating theoperating sequence of apparatus embodying the principles of the presentinvention;

FIG. 3 is a schematic circuit diagram showing a switch arrangement forentering data into apparatus for weighing, computing a value andprinting a label for each of a plurality of successive articles;

FIG. 3A shows a multiplex interface between the analog-to-digitalconverter and the microcomputer multiplex input interface.

FIG. 4, composed of FIGS. 4A - 4C, is a schematic logic diagram ofcircuitry for controlling the operating sequence and computing a valuein apparatus for weighing, computing a value and printing a label foreach of a plurality of successive articles;

FIG. 5 is a schematic logic diagram showing multiplexing circuitry forsupplying data to a digital weight display;

FIG. 6 is a block diagram of a printer for use in apparatus according tothe present invention; and

FIG. 7 is a diagram of one possible memory location arrangement in therandom access memory in the microcomputer of the exemplary apparatus ofthe present invention.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

Referring now to the drawings and particularly to FIG. 1, a blockdiagram is shown of apparatus 10 embodying the principles of the presentinvention for weighing articles and, for each weighed article, forcomputing a value based upon a predetermined price per unit weight andsubsequently printing an article label bearing the weight, the price perunit weight and the computed value for the article. The weight of eacharticle is measured by a scale 11. Although the scale 11 may be ofvarious known designs using mechanics, optics and electronics, it ispreferably an electronic scale of the type shown in U.S. Pat. No.3,709,309 which issued on Jan. 9, 1973 to Williams, Jr. et al, and thedisclosure of such patent is incorporated herein.

The scale 11 generally comprises a load cell 12 which generates ananalog output signal proportional to the weight of an article placed ona platter or weight platform 13. The analog output from the load cell 12is applied to an analog-to-digital converter 14 which has a digitaloutput corresponding to the gross weight of the article on the platter13. The digital weight signal from the converter 14 is preferably in abinary coded decimal (BCD) format which is particularly desirable foruse in computing an article value. The binary coded decimal (BCD) formatcomprises four binary digits for each decimal digit. The weights givento the binary digits are 1, 2, 4, 8 respectively of each decimal digit.The converter 14 may be arranged to provide any desired number ofdecimal digits, depending upon the maximum weight to be weighed on thescale and also upon an increment represented by the least significantdecimal digit. In the exemplary embodiment described herein, as well asin the exemplary embodiment set forth in the above-identified patent toWilliams, Jr. et al, it is assumed that five decimal digits will besupplied by the analog-to-digital converter 14.

The above-identified patent to Williams, Jr. et al discloses circuitryfor automatically canceling unwanted direct current signals from thedirect current or analog signals from the load cell, sensor, transducer,or strain gauge. In addition, this patent discloses circuitry forautomatically zeroing the analog portion of the system while thetransducer output is momentarily interrupted and for filling in gaps inthe analog signal resulting from interruption of the transducer orstrain gauge output.

As explained in the above-identified patent to Williams, Jr. et al, itis sometimes desirable to indicate a negative weight from the overallarrangement from the scale load cell through the converter and digitalcontrol arrangement. Thus, when the scale has been corrected to read netweight and the container and the commodity and both removed from theplatter, the scale should indicate a negative weight equal to the weightof the container which is the tare weight for which the scale has beenadjusted. The overall arrangement in accordance with the exemplaryembodiment of this invention is accordingly arranged to indicate anegative weight under these circumstances and also under otherconditions described herein.

However, the arrangement for making the various analog correctionsdescribed in the above-identified patent to Williams, Jr. et al do notprevent the zero output display of the scale from varying or wanderingin a random manner.

In accordance with the present invention, the digital output or displayfrom the scale mechanism is further corrected in the manner describedherein to correct for the random wandering of the zero display of thescale.

A digital weight signal from the scale 11 is applied to a control unit15 through interface circuits of FIG. 3A and circuits 24 of FIG. 4B. Thecontrol unit 15 includes an input/output buffer and memory 16 whichreceives the digital weight data through the interface circuits of FIG.3A and the circuits 24 from the scale 11. Data input switches 17 arealso connected to the input/output buffer and memory 16. The data inputswitches 17 include a manually operated keyboard for entering pricedata, a printer mode switch and tare weight switches. The input/outputbuffer and memory 16 functions as an interface with an arithmetic logicunit 18. A sequence controller 19 causes the arithmetic logic unit 18and data memory or registers 20 to compute the value of each weighedarticle and to supply such value through the input/output buffer andmemory 16 to a printer 21. The arithmetic logic unit 18, the sequencecontroller 19 and the data registers 20 are preferably included in anintegrated circuit microcomputer, as will be discussed in greater detailbelow.

The value is computed from a price per unit weight which is obtainedeither from the data input switches 17 or from a commodity plateinserted into the printer 21. The commodity plate automatically suppliesprice information to the input/output buffer 16 in a manner similar tothat described in U.S. Pat. No. 3,459,272 which issued to Susor on Aug.5, 1969 and the disclosure of such Susor patent is incorporated herein.The commodity plate includes raised type for use in printing thecommodity or article name on a label. Price per unit weight informationis encoded on the commodity plate by means of the presence or absence ofa plurality of holes or notches at predetermined locations. An opticalor other suitable type of reader is provided in the printer 21 forsensing the presence or absence of the holes and for converting theprice per unit weight information to a BCD output. The weight data fromthe scale is corrected for any tare weight and zero error by thearithmetic logic unit 18 and supplied to the printer 21 and to a digitalweight display 22. After a steady state weight reading is received bythe logic unit 15 from the scale 11, the sequence controller 19 causesthe arithmetic logic unit 18 to compute an article value. The computedarticle value, the net article weight and the price per unit weightinformation are used by the printer 21. The sequence controller 19controls data output to the printer and initiates printing a label.

After a label is printed, the sequence controller 19 will normallyinhibit the arithmetic logic unit 18 until the label has been removedfrom the printer 21 and a motion - no motion cycle has appeared on thescale 11 to indicate that the weighed article has been removed and a newarticle has been placed on the scale 11. The sequence controller 19 mayalso inhibit the arithmetic logic unit 18 in the event of the occurrenceof various conditions. For example, if the price or tare information ischanged, the apparatus 10 is adapted to go into a "lock" condition whichprevents printing a label until a "lock" switch is manually actuated toextinguish an indicator light. Such an interlock prevents an accidentalchange in price or tare weight data, as when an operator accidentallybumps one of the switches 17. Another interlock may be provided toprevent printing a label if data print wheels are not properly set up tothe correct value, weight and price data. Still another interlock mayprevent printing an erroneous label in the vent that either the maximumweight capacity of the scale 11 or the maximum value capacity has beenexceeded.

For convenience, the apparatus 10 is adapted for operating in severaldifferent modes. The different modes of operation affect the manner inwhich the printer 21 prints a label. The data input switches 17 includethe mode switch which permits selecting either "single," "demand" or a"continuous" mode of operation for printing labels in which the value iscomputed for each weighed article. In the single mode of operation, theapparatus 10 must be manually actuated for each label which is printed.In the demand mode of operation, a new label is printed each time aprinted label is removed from the printer 21 and the scale 11 has gonethrough a motion - no motion cycle to cause the computation of a newvalue. In the continuous mode of operation, the printer 21 willcontinuously print lables all bearing the same weight, price per unitweight and value. The mode switch may further include "price by count"modes of "single," "demand" and "continuous." In the price by count modeof operation, the printer 21 will print labels bearing a count or factorof the number of pieces in each article or package to be labeled and thetotal price for this number of pieces. For example, a grocery store maypackage six oranges or six pears together. If the package price is, forexample, six for $1.29, then the label will be printed bearing thelegend "$1.29" in the place of the article value and "6/$1.29" in placeof the price per unit weight.

In the following description of an exemplary embodiment of the presentinvention, it is assumed that the automatic zero correction feature willwork within a range of -0.005 pounds and +0.005 pounds. However, theselimits may obviously be changed to any desired value. In addition, anexpanded range switch or button is provided which will allow the zerocorrecting feature to operate within other weight limits. For example,by operating this expanded range button under certain circumstances, theautomatic zero correcting arrangement may be employed to correct in therange from 0.105 pounds and 0.095 pounds. However, the arrangement inaccordance with this invention is also arranged to prevent any operationof the zero correcting arrangement if the indication of the weight onthe scale platter or pan exceeds 0.6 pounds.

Also, a ready lamp or other indicator is provided which is turned onwhen indication from the scale is within +0.002 pounds and -0.002 poundsfor a predetermined interval of time. The lamp is employed to indicatethat the scale is properly corrected and in condition to weigh anotherobject or commodity. The automatic zero wander correction does not stopat 0.002 pounds, but continues on to be corrected to zero accurately.The automatically operated correcting feature operates sufficientlyrapid so that correction will all be completed prior to the time theready lamp is turned on and thus prior to the time an object orcommodity to be weighed is placed on the platter or pan to be weighed.

It is obvious that the predetermined limits of -0.002 and +0.002 pounds,+0.005 pounds and -0.005 pounds and the limits of 0.6 and -0.6 poundhave been arbitrarily set or selected and that any other set of suitablelimits may be selected and provided by obvious minor changes in thecontrol equipment in accordance with the present invention.

Turning now to FIGS. 2A through 2J, a flow diagram is shown for anexemplary operating sequence of the apparatus 10 for measuring theweight of an article, computing from the measured weight and a price perunit weight the article value and printing an article label. The flowdiagram consists of a series of diamonds or rhombuses and rectangles.Each diamond corresponds to a question having either a yes or a noanswer which may be obtained by conventional methods. Each rectangularblock corresponds to the performance of a specific function such ascausing a label to be printed. The numbers placed in the circles to thetop and left of the blocks represent input locations. For example, an A2in a circle on the left of the flow diagram in FIG. 2A represents aninput to the second block from the top in sheet A of FIG. 2. The numbersin the circles to the right of the blocks in the flow diagram representan output connected to a different location in the flow diagram. Forexample, the first or uppermost block in FIG. 2A has an output to E1 ifthe answer to the question is no. This indicates that if the answer isno, a jump is made to E1 or the input on the first block in sheet E ofFIG. 2.

For convenience, FIG. 2 has been separated into parts A through J.Generally speaking, FIG. 2A covers the basic cycling of the apparatus10. Upon the occurrence of a predetermined sequence of conditions, thecycle is completed with a print pulse. FIG. 2B represents the logic of acheck of various interlocks for the occurrence of new data. FIG. 2Cshows the sequence of operations for the operation of the lock switchwhich must be pressed when data is changed and the printer 21 is in the"single" mode of operation. FIG. 2D shows the logic for checking thesetting of the service switch which affects the weight display 22 andfor checking for the presence of excess weight and excess value. FIG. 2Egenerally represents the operation of the scale motion detector. FIG. 2Fshows the operation of the "expand" switch which permits checking theaccuracy of scale zero and of the auto-zero capture range expand switch.FIG. 2G shows the operation of the auto-zero correction circuitry, ofthe price by count logic and of the value computation. FIG. 2H shows themanner in which the condition of value, price and weight blankingswitches are checked and the sequence in which the outputs are actuallyblanked. FIG. 2I shows the manner in which tare weight is manuallyentered into the apparatus 10. FIG. 2J shows the sequence of operationsfor transferring weight signals from the analog-to-digital converter tothe microcomputer.

As previously indicated, FIG. 2A shows the basic operating cycle for theapparatus 10. Each new cycle is initiated at the input A1 to a block 25.If motion has been present on the output from the scale 11 during theprevious cycle of the apparatus 10, a motion flag MOTNF will be set. Themotion flag MOTNF may, for example, consist of a bit stored in a memoryor the state of a flip-flop or a latch. If the motion flag MOTNF is notset, the logic jumps to the E1 input while if the motion flag MOTNF isset, the logic proceeds to a block 26. The logic must proceed throughthe block 26 before a label can be printed. Thus, the block 25 requiresa motion - no motion cycle before a label is printed. In the block 26,the presence of a motion flag MOTNF is again checked. If the flag isstill present, the cycle again turns to the E1 input while if the flagis not present, the logic proceeds to a block 27 which checks to see ifthe printer is in a demand or continuous mode of operation as set on amode switch. If the system is operating in a demand or continuous mode,the logic proceeds to the A5 input, while if it is in a single mode,logic proceeds to a block 28.

In the block 28, a check is made on whether or not the printer 21 is setup to inhibit the recognition of a motion - no motion function if apreviously printed label has not been removed from the printer. If themotion detector is not inhibited, logic proceeds to A7 while if it isinhibited by the printer 21, a check is made in block 29 on whether ornot a new weight measurement is required by the printer 21 due to a lackof verification in the data supplied to the printer 21. If a reweigh isrequired, the logic proceeds to A7 while if reweigh is not required, ablock 30 checks to see if print data is stored in the printer 21. Ifprint data is stored, the system returns to A1 while if print data isnot stored, it proceeds to a block 31 which checks on whether or not a"no tare weight" key has been pressed. If the no tare key is pressed, ablock 32 checks to see if the price per pound data is equal to zero. Ifthe price per pound data is equal to zero, a block 33 outputs a "print"pulse to the printer 21 for printing a label and the cycle returns toA1. This function is provided to allow printing of labels when theweight is equal to or less than 0.1 pound, for testing.

If either the no tare key is not pressed or the price per pound is notequal to zero, the system proceeds from the blocks 31 or 32,respectively, to a block 34 which checks to see if the net weight fromthe scale 11 is greater than 0.1 pound. If the net weight is not greaterthan 0.1 pound, it is assumed that an article is not present on thescale platform 13 and the system returns to A1. If an article greaterthan one-tenth pound is present on the scale platform 13, a block 35checks to see if a SET latch or flip-flop is true. If it is true, itindicates that the system interlocks have been broken and the cyclereturns to A1. If SET is not true, a block 36 checks to see if the netweight is positive. If the net weight should for any reason be negative,such as when a tare weight is entered into the apparatus 10 and apackage or article has not yet been placed upon the scale platform 13,the cycle returns to A1. If the net weight is positive, a block 37checks to see if an OVERCAP latch or flip-flop is true. OVERCAP is truedwhen the weight capacity of the apparatus 10 has been exceeded.

For the following description, it will be assumed that the apparatus 10is capable of measuring up to thirty pounds so that OVERCAP will be trueif a weight greater than thirty pounds is placed upon the scale platform13. If OVERCAP is true, the cycle returns to A1. If the capacity of theapparatus 10 has not been exceeded, a "print" pulse is outputed at ablock 38. From block 38 control is returned to A1. When the control istransferred to A15, block 39 causes the system to read all externalinputs including the mode switch, the tare weight switches, the priceswitches, the price by count switches, the auto-price input from theprinter and any weight input from the scale 11. After the externalinputs are read, a block 40 checks to see if the apparatus 10 is in a"price by count" mode. If the apparatus 10 is in the price by countmode, logic proceeds to B3 while if it is not in this mode, a block 41checks to see if auto-price data has been received from the printer 21.As previously indicated, the auto-price data may be supplied from acommodity plate inserted into the printer 21. If auto-price data isreceived from the printer 21, a block 42 checks to see if the price dataduring the last cycle was also auto-price data received from the printer21. If not, the system proceeds to B7. If the last price was also fromthe printer, a block 43 reads and stores the auto-price data inputs fromthe printer 21. The system then proceeds to B1.

Turning now to FIG. 2B, the logic is shown for checking the variousinterlocks. From the input B1, a block 46 checks for correct parity inauto-price data received from the printer. If there is a parity error,the logic proceeds to B7. If there is no parity error, the logicproceeds to a block 47. If the printer 21 is operating in a manual mode,the diagram in FIG. 2B is entered through B2, wherein a block 48 checkson whether or not the last cycle was also in the manual mode. If not,the cycle proceeds to B7 while if the last cycle was also manual, thelogic also proceeds to the block 47. The block 47 checks on whether ornot the price data input has changed. If no change has occurred, a block49 checks an interlock on the printer door. If the printer door is open,the logic proceeds to B7 while if it is not open, a check is made by ablock 50 on whether or not an auto-zero inhibit signal is received fromthe printer 21. If no inhibit signal is received, the cycle proceeds toB8.

Returning to the block 47, if the price input data has changed, at ablock 51 the new price input data is moved to a price per pound outputmemory, hereinafter referred to as "p/LB OUT." The cycle then proceedsto a block 52 and an interlock flag INTF is set. The cycle also proceedsto the block 52 from the block 50 if an auto-zero inhibit is receivedfrom the printer 21. The interlock flag INTF may consist of the settingof a latch or a flip-flop or a bit stored in a memory. The presence ofthe flag indicates the occurrence of an interlock such as a change inthe printer mode, the opening of the printer door or the presence of anauto-zero inhibit signal. After the interlock flag INTF is set at theblock 52, a block 53 checks to see if an "auto-tare" switch has beenactuated. If not, the logic proceeds to I1 for manually entering a tareweight. If the auto-tare switch has been pushed, a block 54 updates thetare weight by storing the current measured weight in a TARE memory andagain sets the interlock flag INTF. A block 55 then checks to see if theprint mode has changed. If not, the logic proceeds to B12 while if themode has changed, a block 56 updates a "print mode out" signal whichindicates when the printer 21 is in the demand or continuous modes ofoperation. A check is then made at a block 57 to see if the interlockflag INTF is set. If not, the logic jumps to C1. If the interlock flagINTF was set, a block 58 clears the interlock flag INTF and sets an"initialize" flag INITF. Thus, the initialize flag INITF is set whenevereither the price input or the tare weight input has changed. This flaginhibits the printing of a label until the lock switch is manuallyactuated, thus preventing an erroneous change in the tare weight orprice data. After the initialize flag INITF is set, a block 59 trues theSET latch to indicate that the interlocks have been broken and thesystem proceeds to C5.

FIG. 2C shows logic relating to operation of the lock switch which mustbe actuated when the initialize flag INITF is set. A block 62 checks tosee if the initialize flag INITF is set. If not, the cycle jumps to C5.If the initialize flag INITF is set, a block 63 checks to see if themode switch is in the demand or continuous mode. If the mode switch isin either of these modes, the cycle again proceeds to C5. If not, ablock 64 checks to see if the lock switch is pressed. If not, the cycleproceeds to C5. If the lock switch is pressed, a block 65 clears theinitialize flag INITF and clears the SET latch and continues with the C5input to a block 66. The block 66 returns the cycle back to either A1 orA2, whichever was the original point of origin for arriving to the block66.

The logic of FIG. 2D checks the setting of a service switch whichpermits isolating price and value errors in printed labels between theprinter and the logic unit which calculates and stores this data, andalso checks for the presence of either an excessive weight or anexcessive value which may cause an error in the output from theapparatus 10. From the D1 input, a block 69 checks to see if the serviceswitch is in a "display price" position. If so, a block 70 transfers theprice data stored in the P/LB OUT memory into a WEIGHT OUT memorywherein such price data is displayed on the digital weight display 22.If the service switch was not in the "display price" position, a block71 checks to see if the service switch is in the "display value"position. If not, the cycle proceeds to D3 while if it is in thisposition, the cycle proceeds to a block 72 which causes a transfer ofvalue data stored in a VALUE OUT memory into the WEIGHT OUT memory fordisplaying the value data on the digital weight display 22. Thus, if anerror is present in the price shown on the printed label and the serviceswitch is in the display price position, a comparison may readily bemade between the price appearing on the digital weight display 22 andthe price appearing on the printed label. If these prices are notidentical, the serviceman will know that the error is due to a fault inthe printer 21. If the data is identical, the serviceman will know thatthe error is caused in the logic unit 15. A similar check may be made onthe computed value.

The D3 input as well as the outputs from the blocks 70 and 72 areapplied to a block 73 which turns on a "ZERO" light. The ZERO lightindicates that the scale is properly zeroed to within 1/4 of the leastsignificant displayed weight digit. A block 74 then outputs all data andthe printer mode to the printer 21. Subsequently, a block 75 checks tosee if the maximum value capacity of the apparatus 10 has been exceeded.If the maximum value has been exceeded, a block 76 will set an OVERVALUElatch or flip-flop or store a bit in a memory location. After the block76 has set OVERVALUE or if the logic jumped to D7 because the maximumvalue capacity was not exceeded, a block 77 checks to see if the maximumweight capacity of the scale 11 has been exceeded. If not, the cyclewill proceed to C5 where it is returned to either A1 or A2. If themaximum capacity of the scale 11 has been exceeded, a block 78 sets anOVERCAP latch or flip-flop or stores a bit in a memory location and anOVERCAPACITY flip-flop or latch is set to turn on an indicator light.The cycle then returns through C5 to either A1 or A2.

In FIG. 2E, a check is made to see if weight data read from the scale 11is legitimate, i.e., no analog-to-digital conversion is occurring in theconverter 14. If not, a check is made on whether or not a zero expandswitch is actuated. If weight data is legitimate, a motion check is madeto see if the data has been consistent or steady for a predeterminednumber of cycles.

From an input E1, a block 81 checks to see if a T1 flag is set. The T1flag is set whenever new weight data has been read from the scale 11into the logic unit 15. If the T1 flag is not set, a block 82 checks tosee if a clock signal T1 is true. A true T1 represents a time intervalduring which weight data is not permitted to change. The apparatus 10may, for example, operate on a 200 millisecond cycle. T1 may be set truefor an arbitrary time interval, such as true for 60 milliseconds out ofeach cycle and false for the remaining 140 milliseconds. If T1 is true,logic proceeds from the block 82 to E4, while if T1 is not true a block83 sets the T1 flag and the logic proceeds to E4. At E4, a block 84checks to see if a "zero expand" switch is actuated. If not, the logicreturns to A15 while if the zero expand switch is actuated, a block 85sets the interlock flag INTF and the logic returns to A15. The zeroexpand switch is used for checking the accuracy and adjusting the weightzero when no weight is present on the platform 13 on the scale 11. Whenthe zero expand switch is closed, the weight displayed on the digitalweight display 22 is shifted by one decimal point. Thus, if the scalenormally has a maximum reading of 30.00 pounds, the displayed weightwill be shifted over to display X.XXX pounds or to display as low as1/1000th of a pound.

If the T1 flag T1F is set when the logic reaches the block 81, a block86 checks to see if T1 is true. If not, the logic returns to E4. If T1is true, a block 87 clears the T1 flag T1F. A block 88 then causes aweight reading to be entered into the logic unit 15. Next block 96causes the tare timer state to be read out from the tare timer storagespace in the RAM 187. Then in accordance with block 97, if the count inthe tare timer is not zero it is reduced by one as indicated in block97A and the control advances to block 89. If the count recorded in thetare timer is zero the control advances directly to block 89. After theweight is read out and the tare timer decremented if required asdescribed above, block 89 checks the memory or switches for the settingof the motion detector count and the motion detector band. The motiondetector count is the number of cycles or repetitions which must occurwith no motion present before a label is printed. For example, switchesmay be set to establish that the apparatus 10 must cycle without motionat least twice or at least three times before a label can be printed.The band is the amount of permissible change during a no motioncondition. For example, it may be determined that it is desirable tohave a weight reading maintained within plus or minus 0.005 pound for ano motion condition. This results in a range of 0.01 pound for themotion detector regardless of the measured weight. This arrangementeliminates prior art problems in obtaining a uniform motion detectorsensitivity for all weight measurements. The prior art optical motiondetectors have not had a uniform sensitivity. After the count and bandfor the motion detector are determined, a block 90 calculates the weightminus the sum of the target plus the band. If this value is positive,then motion is present. The block 90 also determines the weight minusthe sum of the target minus the band. If this sum is negative, thenmotion also is present. The target is taken to be the last weightreading.

If the block 90 calculates that there is motion, then a block 91transfers the logic to F1 while if motion is not present, a block 92checks to see if a motion flag MOTNF was set during the last cycle ofthe apparatus 10. If the motion flag is clear, logic proceeds to F2while if a motion flag is present, a block 93 increments by one a nomotion counter. After the counter is incremented, a block 94 comparesthe total count with the no motion count determined at the block 89. Ifthe contents of the counter is not equal to or greater than this count,the cycle proceeds to F2 while if it is greater than or equal to thecount, the motion flag MOTNF is cleared at a block 95. The cycle thenproceeds to F2.

In FIG. 2F, sequence of operations is shown for the operating sequenceof the zero expand, the auto-zero capture range expand and the weightovercapacity check. The F1 input, which is entered if motion is present,is applied to a block 98 which clears the no motion counter and sets themotion flag MOTNF. After the flag is set, a block 99 updates the targetand subtracts a digital weight of eight pounds. The output from the loadcell 12 and the scale 11 preferably is always positive since it is in adigital format. Some types of analog-to-digital converters 14, such as adual slope integrating converter, are more accurate if used in a rangewherein they only have a positive output. This may be accomplished byoffsetting the output from the scale 11 to fall within the range of from8 pounds to 38 pounds. Thus, the zero is arbitrarily offset by 8 pounds.The block 99 subtracts an initial weight of eight pounds from the scalereading to zero the weight signal when no weight is present on theplatter 13. After the eight pounds is subtracted, a block 100 checks tosee whether or not the zero expand switch is actuated or true. If thezero expand switch is actuated, a block 101 moves the four leastsignificant digits of the measured weight, or the digits X.XXX pounds,to the WEIGHT OUT memory and clears an AUTO-ZERO correction counter.Thus, the digital weight display 22 will now show the true zero weightsetting of the apparatus 10 to within one-tenth of a normal weightgraduation. Since the auto-zero operation is inhibited, a block 102turns off the ZERO light and logic jumps to D1.

If the zero expand switch is not closed, sequence proceeds from theblock 100 to a block 103 which checks to see if an "auto-zero capturerange expand" switch is closed. If not, sequence proceeds to F6.Normally, the weight reading used by the apparatus 10 for calculating avalue is automatically zeroed if the weight from the scale 11 is lessthan 0.005 pound when no weight is present on the platter 13. However,when the autozero capture range expand switch is closed, a block 104will check to determine if the weight recorded in the raw weightregister is equal to or less than 0.6 pound.

If the weight reading is greater than 0.6 pound, the sequence jumps toG7. If it is less, block 106 causes this weight, up to 0.6 pound, to berecorded in the zero error correction register in the AUTO-ZEROregister. The weight is then corrected at a block 105 by the contents ofthe AUTO-ZERO register and moved to the WEIGHT OUT memory.

After the zero is corrected, a check is made to see if the maximumweight capacity of the apparatus 10 has been exceeded. Such maximumcapacity has arbitrarily been set at thirty pounds which is generallysufficient for apparatus of the type described when used in the meatdepartment of a grocery store. A block 107 checks to see if thecorrected weight stored in the WEIGHT OUT memory is greater than 30pounds. If it is, a block 108 sets an OVERCAP latch, flip-flop orsimilar memory device. If the maximum weight is not exceeded, a block109 clears OVERCAP. Blocks 108 and 109 are connected to a block 110which checks to see if a motion flag MOTNF is present. If not, logicproceeds to G1, while if motion is present, a block 111 checks to see ifSET is true. If SET is true, the logic proceeds to G7 while if it is nottrue, a block 112 blanks the weight output and the logic proceeds to D1.

FIG. 2G shows the sequence of operations of the auto-zero correctioncircuitry, of the price by count mode of operation and of the valuecomputation if a mode other than price by count is selected. Acorrection is automatically made to errors in the scale zero when theabsolute value of the previously corrected weight is less than 0.005pound. A total correction may be made up to 0.6 pound in 0.001 poundincrements, or in other suitable incremental values. Furthermore, grosszero corrections of up to 0.6 pound may be made by use of the zerocapture range expand switch which stores correction weight up to 0.6pound to be stored in an AUTO-ZERO memory.

The G1 input to a block 115 is compared to see if the absolute value ofthe corrected weight is less than or equal to 0.005 pound. If not, ablock 116 clears the 1/4 graduation flag to turn off a light whichindicates that the weight reading used by the logic unit 15 forcomputing a value is within 1/4 of one graduation displayed on thedigital weight display 22. From the block 116, sequence of operationsproceeds to G7, skipping any changes in the contents or correctionfactors stored in an AUTO-ZERO correction register. If the absolutevalue of the corrected weight is less than or equal to 0.005 pound, ablock 117 checks to see if the absolute weight is less than or equal to0.002 pound. If not, a block 118 sets the zero count register to 12which in turn causes the 1/4 graduation indicator light to be turned offlater in the cycle.

If the absolute value of the corrected weight is less than 0.002 pound,a block 120 indicates that the count stored in the zero count registeris read out of this register but also remains stored in this register.In accordance with block 119, the zero count register is checked todetermine if zero is recorded in this register. If the count is zero,block 132 checks the weight to determine if the weight is zero. If itis, the sequence jumps to G7. If the weight is not zero, the sequencecontinues to block 121. If the count in the zero count register is notzero, block 114 indicates that the count in this register is incrementedby one. Thereafter, the sequence goes to block 132 and then asdescribed.

After the 1/4 graduation flag is set at the block 120, or after thelogic has jumped to G5, a block 121 checks to see if the total auto-zerocorrection factor stored in the AUTO-ZERO register is less than or equalto 0.6 pound, the maximum permissible correction factor. If thecorrection factor is greater than or equal to 0.6 pound, no change ismade in the correction factor and the logic jumps to G7, while if it isless than 0.6 pound the factor stored in AUTO-ZERO is modified by 0.001pound at a block 122. After the sequence of operations jumps to G7 orafter the AUTO-ZERO correction factor is modified in the block 122, ablock 123 causes the tare weight stored in the TARE memory to besubtracted from the corrected scale weight and the four most significantweight digits are moved to WEIGHT OUT. Thus, it will be apparent that anauto-zero correction is made regardless of the fact that a tare weightmay have previously been entered into the apparatus 10.

After weight data is stored in WEIGHT OUT, a block 124 checks to see ifthe printer mode switch has been set to a price by count mode ofoperation. If not, the logic jumps to G12 and subsequently a value iscomputed. If the apparatus 10 is in a price by count mode, a block 125causes a factor or count received from the price by count switch to bestored in the P/LB OUT memory for supplying to the printer. A block 126then checks to see if the price by count factor has changed from thelast cycle of the apparatus 10. If a change has occurred, a jump is madeto A15 and all external inputs are again read. If no change hasoccurred, a block 127 causes the price per pound data entered throughthe price switches to be stored in the VALUE OUT memory. If the logichas jumped to G12 and price per pound data from the switches or from theprinter is present, the price per pound data is moved to the P/LB OUTmemory location at a block 128 and zeros are forced into a registerwhich stores the price by count factor read from the input switches 17.A block 129 then computes a value by multiplying the contents of theP/LB OUT memory by the contents of the WEIGHT OUT memory and stores theanswer in the VALUE OUT memory. After the value is computed and stored,a block 130 compares this value with $100, the maximum value capacity ofthe apparatus 10. This maximum value has been arbitrarily selected tolimit the number of print wheels required by the printer since measuringapparatus of this type, when used for labeling meat in the meatdepartment of a grocery store, will normally not be required to exceed$100. If the computed value is greater than $100, a block 131 writeszeros in the VALUE OUT memory and the logic jumps to C5 while if themaximum permissible value has not been exceeded, the logic jumps to H1.

In some instances, an operator of the apparatus 10 may wish to print alabel which does not include all three of the price, the weight and thevalue. The weight, for example, is blanked whenever the apparatus 10 isoperating in a price by count mode. Or, it may be desired to print alabel bearing only the weight. This may be desirable in a wholesaleoperation where the wholesale purchaser will reprice the article forretail sales. Therefore, the apparatus 10 may be provided with manualswitches which permit selectively blanking the price, the weight and thevalue from the printed label. The logic for performing these functionsis shown in FIG. 2H.

The H1 input is connected to a block 134 which checks to see if a "blankprice" switch has been actuated. If the switch is actuated, a block 135causes blanks or numbers which index the print wheels to blank spaces tobe stored in the P/LB OUT memory location. If the blank price switch isnot actuated, or after blanks have been stored in the P/LB OUT memory, ablock 136 checks to see if a "blank weight" switch has been actuated. Ifthe blank weight switch is actuated, a block 137 checks to see if theapparatus 10 is operating in a price by count mode. If the apparatus 10is in the price by count mode, the weight will already have been blankedand logic jumps to H6 while if it is not in the price by count mode, ablock 138 blanks the WEIGHT OUT memory. If the blank weight switch wasnot actuated, a block 139 checks to see if the scale is in the price bycount mode. If not, logic jumps to H6 while if it is in this mode, theblock 138 will blank the WEIGHT OUT memory. If the WEIGHT OUT memory hasbeen blanked or the logic has jumped to H6, a block 140 checks to see ifa "blank value" switch has been actuated and, if not, the logic jumps toD1 while if it is actuated, a block 141 blanks the VALUE OUT memory andthe logic then jumps to D1.

FIG. 2I shows the manner in which the tare weight is manually enteredinto the apparatus 10. The tare weight, which is stored in the TAREmemory, is subtracted from the measured gross article weight forobtaining a net weight used in computing a value. A check is made at ablock 144 to see if a "no tare" switch has been pushed. If the no tareswitch is pushed, the TARE memory is cleared and the interlock flag INTFis set at a block 145 and the logic then jumps to B10. If the no tareswitch was not pushed when the logic was at the block 144, a block 146checks to see if any other tare switch is pushed. If not, the logicjumps to B10 while if a tare switch is pushed, the block 147 checks tosee if a three second time interval has elapsed since the last tareswitch was pushed. If three seconds has elapsed, a block 148 clears theTARE memory and, subsequently, the tare weight represented by the pushedtare switch is stored in the TARE memory and the interlock flag INTF isset. If the three second interval has not elapsed when the block 147 isreached, the contents of the TARE memory are updated by adding the tarevalue represented by the pushed tare switch to the contents of the TAREmemory. Thus, the tare weight stored in the TARE memory will thenrepresent the accumulation of tare weights from two tare switches. Forexample, an operator may push a 0.10 pound tare switch and a 0.06 poundtare switch within a three second time interval and the total tareweight stored in the TARE memory will equal 0.16 pound. From the block149, the logic returns to B10. The three second time interval wasselected on the basis that most people can select and push two switchesin this interval. Of course, a different time interval may be used.

FIG. 2J shows an exemplary sub-routine or sequence of operations forcausing weight signals received from the analog-to-digital converter tobe entered in the weight registers of the microprocessor employed in thepresent invention. The subroutine or sequence of operations shown inFIG. 2J are represented in FIG. 2E by block 88.

The remaining drawings show details of logic and circuitry of anexemplary embodiment of the invention for performing the functionsdescribed in the description of FIG. 2. Turning first to FIG. 3, theinput switches 17 including the price, printer mode and tare weight datainput switches are shown in detail. Price by count data, price per unitweight data, tare weight data and printer mode data is all supplied tothe input/output buffer and memory 16 in the control unit 15 on nineswitch buses 155 which represent the digits one through nine. It will beapparent that no bus is needed for a zero entry which corresponds to theabsence of a signal on any of the nine buses 155. When the apparatus 10is operated in a price by count mode, a count or factor is enteredthrough a price by count switch 156. The price by count switch 156 is asa two-wafer or two-pole rotary switch having eleven contacts forselectively entering a count two through a count twelve. It will beappreciated that a count of one would not normally be used nor is therenormally a need for a count greater than 12, although this may beaccomplished by providing additional contacts on the switch 156. A countof two through a count of nine is entered into the control unit 15 bysetting the switch 156 and strobing or grounding a strobe line 157 whilea count of 10, 11 or 12 is entered by setting the switch 156 andstrobing a strobe line 158. When the price by count switch 156 is set toa factor between two and nine, a signal on the strobe line 157 causes anappropriate output on one of the nine switch buses 155. Similarly, whena signal is applied on the strobe line 158 and the price by count switch156 is set to a factor of 10, 11 or 12, a signal will also appear on oneof the switch buses 155.

The apparatus 10 is designed for calculating an article value from priceper unit weight data having three significant digits or from $0.01 up to$9.99 per pound. The price per unit weight data is manually enteredthrough three switches 159-161. Each of the price switches 159-161 is aten-contact rotary switch. A contact representing zero is not connectedwhile contacts on the switches representing the digits one through nineare connected to corresponding ones of the nine switch buses 155. Theswitch 159 is used for entering pennies, or the least significant digitof the price data. A strobe line 162 is connected for providing a signalon the common terminal of the penny switch 159. When a signal is appliedon the strobe line 162, the penny price data is entered on the connectedone of the switch buses 155. The switch 160 is provided for enteringdimes price data when a signal is received on a dime strobe line 163.Similarly, the switch 161 is connected for supplying dollar price datawhen a signal is received on a strobe line 164. Thus, price data up to amaximum of $9.99 per pound may be entered through the three priceswitches 159-161. Of course, it will be apparent that the number ofprice switches may be varied to meet other requirements for theapparatus 10 and the monetary units represented by the price switchesmay be changed to the local currency where the apparatus 10 is used.

Tare weight is entered into the logic unit 15 by means of nine momentarycontact tare switches 165 which enter tare weight in 1/100th poundincrements from 0.01 pound to 0.09 pound and a switch 166 which enters atare weight of 0.10 pound. A signal is periodically applied by the logicunit 15 on a strobe line 167 which is connected to the 1/100th poundtare switches 165. These switches 165 are normally open push buttonswitches. In the event that one of the switches 165 is pushed when asignal appears on the strobe line 167, an output appears on theassociated one of the switch buses 155. A strobe line 168 is connectedto the 0.10 pound tare switch 166, also a push button switch, and to an"auto-tare" switch 170 and a "no tare" switch 171. In the event that anyof the switches 166, 170 or 171 is pushed when a signal appears on thestrobe line 168, an output will appear on an associated one of theswitch buses 155.

The apparatus 10 is designed for operation with a keyboard tare weightranging from a minimum of 0.01 pound to a maximum of 0.19 pound. This isaccomplished by providing a timing circuit in the control unit 15 whichis initiated whenever one of the switches 165 or 166 is actuated. If oneof the switches 165 is actuated and within the measured time intervalthe switch 166 is actuated, the tare weights for the two switches aresummed. Similarly, if the switch 166 is actuated first and within themeasured time interval one of the switches 165 is actuated, the total ofthe two tare weights is again summed. If two of the tare switches 165are actuated within the time interval, only the most recent value isentered. The time interval may, for example, be about three secondswhich should afford sufficient time for an operator to select andactuate two of the tare switches 165 and 166. If a greater time elapses,only the most recent are weight entered through a switch 165 or 166 isaccepted by the control unit 15.

A printer mode switch 172 also supplies data over the switch buses 155.The printer mode switch 172 is a rotary switch having a common terminalconnected to a printer mode strobe 173. When a signal is received overthe strobe 173, an output appears on one of the switch buses 155,depending upon the setting of the mode switch 172. In an exemplaryembodiment of the invention, the printer mode switch permits selectingbetween a "single" mode, a "demand" mode, a "continuous" mode, a "priceby count-single" mode, a "price by count-demand" mode and a "price bycount-continuous" mode. In either of the single modes of operation, asingle label is printed each time an article is weighed. The printer isactuated each time the scale goes through a motion - no motion cycle, avalue is computed and the previous label has been removed from theprinter 21. In the demand modes of operation, labels are printed asprevious ones are removed from the printer. In the continuous modes ofoperation, the printer will continuously print a series of labels havingthe same weight, price per unit weight and value until printing ismanually terminated.

The switches 17 also include an "auto-price" switch 174. When priceinformation is to be supplied automatically from a commodity plate inthe printer, the auto-price switch 174 is actuated. When the switch 174is actuated, an indicator light 175 is automatically illuminated toannunciate this fact. A switch 176 is provided for expanding the capturerange of the auto-zero circuitry from a normal range of zero plus orminus 0.005 pound to up to plus or minus 0.6 pound. The switch 176 is amomentary push button switch. A switch 177 is provided for inhibitingoperation of the auto-zero circuitry to permit government inspectors tocheck the weighing accuracy of the apparatus 10. Finally, a switch 178is provided for expanding the weight reading shown on the digital weightdisplay 22. The zero expand switch is normally used by maintenancepeople in calibrating the zero weight setting for the apparatus 10. Whenthe zero expand switch 178 is actuated, the displayed weight which isnormally in a format of XX.XX pounds is shifted over by one digit todisplay a weight reading of X.XXX pounds. This permits calibrating thescale zero to within 1/1000 of a pound. Finally, the switches 17 includea "lock" switch 179. Any time there is a change in data entered into theapparatus 10 other than weight data, the apparatus 10 moves from what isnormally referred to as a "ready" state to a "set" state to indicatethat an interlock has been broken. The lock switch 179 must be manuallyactuated to return the apparatus 10 to the ready state. Thus, anoperator cannot accidentally bump one of the tare switches 165 and 166or the price switches 159-161 after the apparatus 10 is in the readystate and print erroneous labels.

FIG. 3A shows an exemplary arrangement for multiplexing the outputdecimal digits from the analog-to-digital converter of theabove-identified Williams, Jr. et al patent so that this information maybe transmitted over four data conductors or leads. In addition, fouraddress leads are required to indicate which of the decimal digits isbeing transmitted over the four common leads at any particular instantor interval of time.

While both the above-identified patents to Williams, Jr. el al and thepresent exemplary embodiment of the invention show five decimal digits,it is obvious that any suitable number of decimal digits may be employedmerely by increasing the number of counterstages and latches and relatedequipment.

The arrangement shown in FIG. 3A is controlled by a source of controlsignals 350. This source of signals may be an oscillator or any othersource of control or clock signals which may be derived from theanalog-to-digital converter such as a clock source of this converterwhich would be divided down to a much slower pulse or clock rate.

The clock source 350 is further divided by five by equipment 351 whichmay be of any suitable form. The output of this dividing circuit asshown in FIG. 3A comprises a binary output having conductors 1, 2 and 4.This is the weight of the signals output from the frequency divider 351.These signals are then applied to the multiplexing interface circuits352, 353, 354 and 355 which may be all the same. These devices arearranged to switch the five input leads shown to the one output leadunder control of the input binary address signals on conductors 1, 2 and4. Thus, when the conductors 1, 2 and 4 are all zero, the input leadsA1, A2, A4 and A8 are connected respectively to WT. DATA 1, WT. DATA 2,WT. DATA 4 and WT. DATA 8 leads. When a one signal is applied to theconductor 1 input address conductor and the other two address conductorsare zero, then the B1, B2, B4 and B8 input leads are connected to therespective WT. DATa 1 lead, the WT. DATA 2, WT. DATA 4 and WT. DATA 8conductors, respectively. In a similar manner, the other inputconductors of these switching devices are connected to the output weightdata leads.

The input leads A1, A2, A4 and A8 are connected to the four binaryoutput leads from the first decade of latches 136 of theabove-identified patent to Williams, Jr. et al. Similarly, the inputconductors B1, B2, B4 and B8 are connected to the four binary outputleads from the second decade of latches 137. The remaining input leadsare similarly connected to the corresponding binary leads of the otheroutput decade latches 138, 139 and 140 of the above-identified Williams,Jr. et al patent.

In addition, the output binary coded signals over conductors 1, 2 and 4from the divider 351 are connected to a translating circuit arrangement356 such that when all zeros are applied on the leads 1, 2 and 4, zerowill be also applied to the digit selector leads DIG SEL B, DIG SEL C,DIG SEL D AND DIG SEL E thus indicating that the first decade signalsappear on the weight data leads WT. DATA 1, WT. DATA 2, WT. DATA 4 andWT. DATA 8. When a one is applied to the number one lead, a one orvoltage signal will be applied to the DIG SEL B conductor thusindicating that the B decade signal will be transmitted over the WT.DATA 1, WT. DATA 2, WT. DATA 4 and WT. DATA 8 leads. Similarly, a onesignal will be applied to the digit selector leads C, D and E when thecorresponding weight data signal of these decimal digits is applied tothe WT. DATA 1, WT. DATA 2, WT. DATA 4 and WT. DATa 8 leads.

The switching devices for switching any one of the input lines to anoutput line are similar to the eight-line to one-line decoders 198, 199,200, 202 of FIG. 4B except that the last three of the eight-lineconductors are not connected. Similarly, the dividing arrangements 351and the translating arrangement 356 are well-known and commerciallyavailable.

Details of an exemplary control unit 15 are shown in FIG. 4. FIG. 4consists of FIG. 4A, FIG. 4B and FIG. 4C which are arranged as shown onthe first sheet of the drawings. In an exemplary embodiment of theinvention the control unit 15 is a microcomputer 185 which functions tocompute the value of each weighed article and to control the operatingsequence of the apparatus 10. The microcomputer 185, for example, may beof a type commercially available in integrated circuits and in theexemplary embodiment described herein the microcomputer 185 comprises aModel MCS-4 Microcomputer Set manufactured by Intel Corporation of SantaClara, California. Such a microcomputer employed in the exemplaryembodiment of the present invention described herein includes a centralprocessing unit (CPU) 186, a random access memory (RAM) 187 and fiveread only memories (ROM) 188-192. In the exemplary arrangement describedherein, the CPU 186 is an Intel Type 4004 integrated circuit, the RAM187 is an Intel Type 4002 integrated circuit and the ROM's 188-192 areIntel Type 4001 integrated circuits. However, it will be appreciatedthat other commercially available integrated circuit microcomputers orother types of commercially available computers will operate inaccordance with the principles described herein.

These various CPU, RAM and ROM units are interconnected in the mannershown in FIG. 4A, as required in order for these units to cooperate onewith another as required by the circuit configurations of these standardcommercially available units. The connections are clearly described inthe Users Manual for the MCS-4 Microcomputer Set published by the IntelCorporation. Briefly, the ROM's, RAM and the CPU are all interconnectedin parallel by the data bus system shown at the top of FIG. 4A. Theseconnections are in accordance with the requirements of the computer ascommercially available. These connections permit the cooperation betweenthe ROM's, the RAM and the CPU. Thus, the CPU will transmit an addressover the bus system which defines a storage space in one of the ROM's,for example. The ROM having this storage space has internal controlcircuitry which will respond to this address and in turn causeinformation stored at the designated address to be transmitted back overthe data bus system to the CPU which then responds to this informationin the usual manner.

The storage portion of the RAM, the ROM's and the sequence controllingportion of the CPU comprise the sequence controller 19 shown in FIG. 1.Arithmetic unit 18 of FIG. 1 comprises the arithmetic unit of the CPU186. The data registers 20 also comprise registers in the CPU 186 andthe registers in the RAM 187. Input/output ports of the ROM's 188-192and the RAM 187 and the related equipment comprise the input/outputbuffer and memory 16 shown in FIG. 1.

The read only memory units referred to herein as ROM's 188-192 storefixed data and also store a series of control orders or instructions forcontrolling the operating sequence of the entire apparatus 10. Theseorders or instructions, as is well understood by persons of ordinaryskill in the programming and computer art, control the centralprocessing unit CPU 186. These orders or instructions are readilyobtained by persons of ordinary skill in the programming and computerart from the flow charts of FIG. 2A-2J by translation of the flow chartsinto computer language as required by the particular microcomputer andset forth in the instructions in the users manual for the respectivecomputer. A program listing for performing the operations specified inFIGS. 2A-2J is attached as an Appendix to this specification. Theprogram in the Appendix is in the language required for an Intel MCS-4microcomputer, as specified in the Users Manual for the MCS-4Microcomputer Set.

FIG. 7 shows the storage areas of the RAM 187 and the storage areasassigned to various registers for controlling input and output data, aswell as process data, so that the data control apparatus will operate toautomatically correct the zero indication of the scale in accordancewith the present invention.

The control orders or instructions control the CPU 186 so that it willobtain the necessary fixed information from the ROM's 188-192 as well asthe required control orders and instructions and obtain the data fromthe RAM 187 and from the various input devices so that the correctweight of each weighed article will be accurately determined and then,after various conditions are met, its value computed, and after thevalue is computed and various other conditions are met, causes a labelto be printed.

The data used by the microcomputer 185 consists of data from the switchbuses 155, data from the scale 11, data from the printer 21 and datafrom various interlocks. Four address outputs 193 from the RAM 187 areconnected through inverters 194 to four address buses 195. Addressinformation and other data supplied from the RAM 187 to the addressbuses 195 determines the data supplied to the microcomputer 185 and thedata supplied from the control unit 15 to the printer 21. External datafrom, for example, the switches 17, is supplied to the microcomputer 185on four input data buses 196 connected to the ROM 188. At the propertime interval, the external input data on the buses 196 passes throughthe ROM 188 onto four input/output data buses 197 connected in parallelwith the five ROM's 188-192, the RAM 187 and the CPU 186.

The external input data is multiplexed onto the buses 196 by means offour 8-line to 1-line decoders 198-201 and a decimal-to-binary codeddecimal (BCD) decoder 202. Each of the four 8-line to 1-line decoders198-201 has a single output connected to a different one of the externalinput data buses 196 connected to the ROM 188. Three of the four dataaddress buses 195 from the RAM 187 are connected in parallel to the fourdecoders 198-201 for selecting the inputs to the decoders 198-201 whichare connected simultaneously to the buses 196. Thus, corresponding onesof the eight inputs to the four decoders 198-201 are connected to theoutputs for such decoders. The zero inputs for each of the four decoders198-201 are connected to the four outputs from the decimal-to-BCDdecoder 202. When a zero address is supplied to the data select inputsof the decoders 198-201, the nine switch buses 155 are connected inseries through the decimal-to-BCD decoder 202 and the line zero inputsof the decoders 198-201 to the four data input buses 196 to themicrocomputer 185.

While the switch buses 155 are connected to the microcomputer 185,signals are sequentially applied to the price switch strobes 162-164,the price by count strobes 157 and 158, the tare switch strobes 167 and168 and the mode switch strobe 173 for entering this data into themicrocomputer 185. The strobe signals are applied on these strobe linesfrom a BCD-to-decimal decoder 203. The ROM 190 has four data outputs 204connected respectively through four inverters 205 to four address buses206. The address buses 206 supply address data to the BCD-to-decimaldecoder 203 for sequentially scanning the ten outputs which strobe theprice switch strobes 162-164, the price by count strobes 157 and 158,the tare switch strobes 167 and 168 and the mode switch strobe 173.

When price per unit weight data is received in an automatic mode from acommodity plate in the printer 21, such data is received over four lines210-213. The four lines 210-213 are connected, respectively to the lineone inputs on the 8-line to 1-line decoders 198-201. Four weight digitselection inputs 214-217 are connected to the line two inputs to thedecoders 198-201, respectively, and four weight data lines 218-221 areconnected, respectively, to the line three inputs to the decoders198-201. The data appearing on the digit selection inputs 214-217identifies which weight digit is present on the weight data lines218-221. The weight data appearing on the lines 218-221 at any giventime is a single digit of weight in a BCD format. If five digits ofweight are to be received from the scale 11, the five weight digits aresequentially read by alternately receiving the digit selection data onthe lines 214-217 and the actual weight data on the lines 218-221.

Interlock information is supplied to the microcomputer 185 by means ofthe line four through line six inputs of the decoders 198-200 and theline four through line seven inputs of the decoder 201. The line fourinput to the decoder 198 receives data from the lock switch 179, theline five input is connected to a motion detector inhibit output from amanual print switch in the printer 21 and the line six input receives a"reweigh" signal from the printer 21. The line four input to the decoder199 is connected to a price contact on a service switch which, whenactuated, connects the line four input to ground. When the serviceswitch is actuated, price data is shifted into a weight memory fordisplaying on the digital weight display 22. The line five input to thedecoder 199 is connected to a lead 222 which receives a signal when alabel is printed, as will be discussed in greater detail below. The linesix input to the decoder 199 is connected to receive an acknowledgmentsignal from the printer 21 when print data for a label has been stored.

The line four input to the decoder 200 is connected to a value contacton the service switch which, when actuated, causes the computed value tobe shown on the digital weight display 22. The line five input to thedecoder 200 is connected to the auto-price switch 174 and through anamplifier 223 to the auto-price indicator 175. When the apparatus 10 isoperated with an auto-price received from the printer 21, a parity checkis made to verify the accuracy of the price per unit weight data. Anauto-price parity signal is applied on a line 224 to the line six inputto the decoder 200. The printer door has an interlock switch connectedto the line four input to the decoder 201. This interlock preventsaccidental actuation of the printer while an operator has the door openfor changing commodity plates or for maintenance. The line five input tothe decoder 201 is connected to the zero expand switch 178 (FIG. 3), theline six input is connected to the T1 clock (not shown) which provides apulse signal to indicate the time interval during which weight data maybe read from the scale 11. As previously indicated in the discussion ofFIG. 2, the T1 clock may have a 200 millisecond cycle, comprised of 60milliseconds in which weight data may be read from the scale 11 and 140milliseconds in which new weight data is measured by the scale 11.Finally, the line seven input to the decoder 201 is connected to thecapture range expand switch 176.

The line seven inputs to the decoders 198-200 are connected to threeswitches 225-227, respectively. One of the switches 225-227 is closed toestablish the number of sequential hits or no motion cycles of themotion detector before a label is printed. The switches may, forexample, indicate that only a single hit is required if the switch 225is closed, two hits are required if the switch 226 is closed and threehits are required if the switch 227 is closed.

Output data from the microcomputer 185 is stored within a random accessmemory 228. Weight, price and computed value data is supplied to the RAM228 from the RAM 187 in the microcomputer 185 over the buses 195.Address information for storing data in the RAM 228 is supplied from theROM 190 over the buses 206. The buses 206 are connected through anaddress selector 229 to address inputs on the RAM 228. The ROM 189 isconnected over a line 230 to an input to the address selector 229 forconnecting the buses 206 to the RAM 228 for supplying a data storage orwrite address or for connecting four buses 231 to the RAM 228 forsupplying a readout address. Thus, when weight data or price data issupplied to the microcomputer 185, such data is also stored in the RAM228 and when a value is computed, the computed value is also stored inthe RAM 228. The ROM 189 enables writing or storing data in the RAM 228by applying a "write enable" signal through an amplifier 236 to a line237. The RAM 228 has four output buses 232 which are connected inparallel for supplying data to the printer 21 and to the weight display22. The output buses 232 are also connected through three exclusive ORgates 233-235 for generating a parity bit from the output data. A BCDsignal is generated in the printer corresponding to the setting of eachprint wheel in the printer 21. A parity bit generated from the settingof each print wheel is compared with the corresponding parity bit fromthe gates 233-235 for verifying the accuracy of the printer setup. Ifthere is a lack of parity, a "reweigh" signal is applied from theprinter 21 to the line six input to the decoder 198.

As indicated above, an output address is supplied to the RAM 228 overthe readout address buses 231. The output address buses 231 are alsoconnected to supply an output data address to the weight display 22 andare connected through amplifiers 240 to supply address data on outputs240' to the printer 21. An address is applied on the buses 231 from afour bit address counter 241. A clock signal is applied from a clocksource (not shown) to a decade counter 242. One output of the counter242 is applied through an inverter 243 for counting up the four bitaddress counter 241. A different output from the decade counter 242 isapplied through an inverter 244 for supplying a clock signal to theprinter 21.

An output 245 from the ROM 189 in the microcomputer 185 is connectedthrough an inverter 246 to a line 247 which enables quad bistablelatches 248. When the latches 248 are enabled, data present on theaddress and data buses 195 from the RAM 187 is set into the latches 248.One output 249 from the latches 248 is a memory update request. Thememory update request line 249 is connected to a NAND gate 250. The NANDgate 250 has an output connected through an AND gate 251 to an enableinput on the four bit address counter 241. The address selection line230 connected from the ROM 189 is also connected to a second input ofthe AND gate 251. A signal is applied on the line 230 to the AND gate251 at the same time the readout address lines 231 are connected to theRAM 228. If the output of the NAND gate 250 is high at the same time,the AND gate 251 will enable the four bit address counter 241 forsupplying a sequence of addresses for reading data from the RAM 228. TheNAND gate 250 also has four inputs connected to the address buses fromthe counter 241 and a printer off input from the printer which is highwhen the printer is off. Thus, when the bistable latches 248 are set toapply a signal on the memory update request line 249 or when the printeris off, the address counter 241 will cycle whenever a signal is receivedfrom the ROM 189 on the line 230. Once a cycle is started by a signal oneither the memory update request line 249 or by a pulse on the printeroff line, the address counter 241 will continue to cycle until all ofthe address buses 231 go to a logic zero.

The bistable latches 248 also include an output 252 which indicates whenthe weight reading is below zero. The output 252 is connected through aninverter 253 to supply a MINUS sign output 254 to the printer 21 andalso to the weight display 22. Still another output 255 from the latches248 is connected through an inveter 256 to an output 257 whichilluminates an out-of-range indicator lamp. A fourth output 258 from thelatches 248 is connected through a NAND gate 259 to illuminate a readyindicator lamp. A "print stored" input 260 from the printer 21 isconnected through an inverter 261 to a second input of the NAND gate259. The output 258 from the latches 248 is also connected through aninverter 262 to a line 263 which supplies a SET signal to the printer.The line 263 is also connected through an amplifier 264 for illuminatinga SET indicator lamp. The printer also supplies the REWEIGH signal on aline 265 through an amplifier 266 to illuminate a "weigh again"indicator lamp, a "take label" signal over a line 267 through anamplifier 268 to a take label indicator lamp and an "add label" signalover a line 269 through an amplifier 270 to an add label indicator lamp.An indicator is also provided for indicating when the apparatus 10 isoperating within the weight zero limit or within a predeterminedfraction of a weight graduation of zero. This has previously beenreferred to as the 1/4 graduation lamp. The ROM 192 has a single output271 which is connected through an inverter 272 to a line 273. The line273 is connected through an inverter 274 for energizing the zero limitindicator lamp.

During normal operation of the microcomputer 185, the ROM 189 applies aperiodic pulse on the line 247 for resetting the bistable latches 248.This pulse will appear once each time the microcomputer 185 goes througha complete program cycle. In typical operation of the microcomputer 185,the pulse will appear at about 0.2 second intervals. However, it ispossible for a noise pulse or some other disturbance to cause thecentral processing unit 186 to end up at an incorrect or nonexistentadddress. In such event, the microcomputer 185 becomes "hung up" and isin effect "dead." When this condition occurs, the microcomputer 185 mustbe restarted before a label can be printed. Timing circuitry is providedfor automatically restarting the microcomputer 185 in the event that twosequential periodic pulses are missing from the line 247.

The line 247 is connected through an inverter 281, a current limitingresistor 282 and a diode 283 to the input of a threshold or leveldetector 284. The input of the threshold detector 284 is also connectedthrough a high value resistor 285 to a voltage source and through acapacitor 286 to ground. When the voltage on the input of the thresholddetector 284 is below a predetermined level, the threshold detector 284will have a high or positive output. However, if the input of thethreshold detector 284 exceeds a predetermined voltage level, the outputof the threshold detector 284 will go negative. The capacitor 286 ischarged at a relatively slow rate through the resistor 285. Each time acycle pulse appears on the line 247, the inverter 281 will have a lowoutput for rapidly discharging the capacitor 286 through the diode 283and the current limiting resistor 282. Under normal operation of themicrocomputer 185, the cycle pulses on the line 247 maintain the chargeon the capacitor 286 below the threshold level of the detector 284.However, in the event of two sequential cycle pulses failing to appearon the line 247, the capacitor 286 will become sufficiently charged asto cause the threshold detector 284 to change states.

When the output of the threshold detector 284 goes negative, a capacitor287 is discharged through a diode 288 and a current limiting resistor289. A decrease in the voltage on the capacitor 287 causes a secondthreshold detector 290 to change from a negative to a positive outputwhich is applied through a resistor 291 to the base of a transistor 292.The transistor 292 then switches states of conduction for applying arecycle or restart signal on a line 293 connected in parallel to the CPU186, the RAM 187 and the ROM's 188-192 in the microcomputer 185. Aresistor 294 and a diode 295 are connected in series between the inputand the output of the threshold detector 284. After the threshold levelis reached and the output of the detector 284 goes negative, thecapacitor 286 is discharged through the resistor 294 and the diode 295until the output from the detector again becomes positive. The capacitor287 is then charged through a resistor 296, thereby causing the outputsof the detector 290 and the transistor 292 to change. If two more cyclepulses are absent from the line 247, the capacitor 286 will again becomecharged sufficiently for the outputs of the detectors 284 and 290 andthe transistor 292 to change states, applying another clear and restartsignal to the microcomputer 185.

FIG. 7 is a diagram showing one of many possible memory locationarrangements in the random access memory RAM 187 of the exemplaryarrangement of the apparatus of the present invention.

As indicated in FIG. 7, the RAM is provided with four memory registerareas. Each of these memory register areas is arranged to store fourbinary digit words which in the exemplary embodiment described hereinusually are coded to represent a decimal digit. Each memory area 16 isarranged to store 16 of these four binary digit numbers or otherinformation. The register areas are selected by address designated "4HIGH" above each one of the areas. Thus, the address of the first areais 0000. The address for the other three memory register areas is shownabove each of these register areas. In addition, each of the four binarydigits forming a word or number in each of the areas is assigned anaddress, which address is shown to the left of the first memory area. Asindicated, the address for the memory areas comprise the first four highnumbers, or binary digits of the address, while the address of theindividual words or numbers within each area is designated by an addressdesignated "4 LOW." Thus, at least certain of the same address symbolsmay be employed to designate both memory areas and also the words withinthe memory areas. Thus, two addresses are distinguished by theirlocation in the addresses as is well known by persons of ordinary skillin the art of microcomputer operation.

The RAM 187 also includes four status registers shown in the lower partof FIG. 7. Each of the status registers has an address similar to thecorresponding memory register area as indicated above each of the statusregisters. The rectangles in the status registers represent a storagespace for a single binary digit or bit. Thus, each of the statusregisters may store four four-bit binary words. In addition, each of thebits of each of the words may be employed to store a binary bit which isindependent of the other binary bits of a particular word at theparticular address. In other words, as indicated, the zero correctionsign bit, 714, is used to store the sign of the zero correction. Thisbit is stored in this bit space independently of the information storedin the other three bits spaces of the last word of the first statusregister.

As indicated in FIG. 7, the first five word spaces 710 in the firstregister space are employed to store the five binary coded decimaldigits of the raw weight received from the weighing apparatus and aredesignated raw register. The next five four-bit register word spaces 735are employed to store the five decimal digits of the motion targetweight. The next word, or register space 726, is employed to store thecount or number of hits employed to determine whether or not there ismotion upon the platter of the scale. The last five word spaces 711 areemployed as a zero correction register and store the five BCD digitsemployed to correct the zero indication of the scale. The other registerspaces are designated to indicate the manner in which the particularregister spaces are employed.

The various status register spaces shown at the bottom of FIG. 7 aresimilarly designated with the name of the bit or bits employed to recordthe various information required to provide the various features of thepresent invention, as described herein.

OPERATION OF THE SYSTEM

As described in the above-identified patent to Williams, Jr. et al, thesensor controlled by the load cell 12 of the scale provides an outputvoltage which represents the load on the load cell, which in turn is afunction of the load on the scale. This output voltage is then amplifiedand processed so as to remove an unwanted direct current component andto reduce or remove unwanted variations in this voltage so that thevoltage accurately represents the load on the load cell and the load onthe scale. This analog voltage is then employed to control ananalog/digital converter 14.

Also the analog-to-digital converter employed in the exemplary systemdescribed herein, in addition to generating a digital signalrepresenting the weight on the scale to be displayed also generates adigital signal representing a fraction of the weight represented by theleast significant digit of the displayed weight. In the exemplaryembodiment described herein, it is assumed that this additional signalrepresents tenths of the weight represented by the least significantdigit displayed. However, this additional digital signal may representany other suitable or desirable fraction of the weight represented bythe least significant digit displayed.

The analog-to-digital converter in effect samples this corrected analogvoltage at repeatedly recurring instants of time. These sample voltagesare then employed to control the output of the digital converter. Thusthe output of the digital converter is a digital signal which accuratelyrepresents the load on the load cell and thus the load on the scale. Inthe exemplary arrangement described in the above-identified patent toWilliams, Jr. et al, and in the exemplary arrangement described herein,the analog-to-digital converter requires a cycle of about 200milliseconds. This cycle is thus repeated approximately five times asecond. Near the end of each cycle of operation of the analog-to-digitalconverting apparatus, this apparatus transfers digital signalsrepresenting the analog weight input to a set of latches. These latchesthen maintain these digital signals for a predetermined interval oftime. During a portion of this interval of time, the analog-to-digitalconverter also applies an output signal to the T1 lead. This T1 signalis obtained from device 100 of FIG. 2 of the above-identified Williams,Jr. et al patent. Thus during the time the output signal is applied tothe T1 conductor, output from the latches remains constant so that theinput to the multiplex switching devices 352, 353, 354 and 355 of FIG.3A remains constant. Consequently, the output signals applied insequence to the weight data conductors WT. DATA 1, WT. DATA 2, WT. DATA4 and WT. DATA 8 represent the respective decimal digits of the outputweight from the analog-to-digital converter. The frequency or speed ofthe clock pulses from source 350 are such that the equipment of FIG. 3Awill operate through a plurality of cycles during the time an outputsignal is applied to the T1 conductor. In other words, each of thebinary representations of the five decimal digits representing theweight will be applied in succcession to the output weight dataconductors WT. DATA 1, WT. DATA 2, WT. DATA 4 and WT. DATA 8 a pluralityof times during the time an output signal is applied to the T1conductor.

Concurrently with the application of the respective decimal digits tothe weight data lines WT. DATA 1, WT. DATA 2, Wt. DATA 4 and WT. DATA 8,corresponding signals are applied either to none or to one of the dataselecting conductors B, C, D and E indicating the specific of the fivedecimal digit signals applied to the weight data conductors WT. DATA 1,WT. DATA 2, WT. DATA 4 and WT. DATA 8 at each of the instants of time.

Assume now that power has been applied to the system so that theanalog-to-digital converter will start to develop an analog conversionand provide a digital output signal after an interval of time. At thesame time, the control equipment 15 will perform an initializingoperation in the usual manner and cause zeros to be stored in each andevery register space in the RAM 187. Thus, zeros will be stored in allof the register spaces of this RAM 187 shown in FIG. 7.

After zeros are stored in all of the register spaces, the control of thesystem is transferred to the main program Al shown in FIG. 2A. Block 25causes the memory space 718 of FIG. 7 to be tested to determine whethera one or a zero is recorded in this space. This space, which isdesignated "MOTNF," represents a motion flag and under the assumedconditions, a zero will be recorded in this space with the result thatthe program is now transferred to El of FIG. 2E. As a result, the systemthen tests the storage space T1F 717 to determine whether a one or zerois stored in this space. Under the assumed conditions, a zero will bestored in this storage spot. This storage space is designated a T1 flag.Since a zero is stored in this storage space, the program proceeds frombox 81 to box 82 where the condition of the T1 clock lead (see thebottom of FIG. 4B) is tested to determine whether one signal or a zerosignal is present on this lead.

Under the assumed conditions, a zero will be present on this lead sothat the program proceeds to block 83. With the zero present on thislead, the analog-to-digital converter indicates that a satisfactoryoutput signal is not present on the output leads from theanalog-to-digital converter.

In block 83 the computer is directed to change the information stored inthe storage bit space 717 to a one, indicating that theanalog-to-digital converter is in the process of providing a validoutput digital signal, but that such signal is not present at this timeon the output leads from the analog-to-digital converter.

From block 83 the control then goes to block 84 where the zero expandswitch is tested. A flag or bit stored in a status register bit space719 indicates the setting of the zero expand switch. Since this switchis assumed to be off, the zero expand is not true and the control isthus transferred to A15 of FIG. 2A at which time the control equipmentsuccessively reads all of the various external inputs and stores theircondition in the third one of the storage registers having an address0010 of FIG. 7. After all of these switches have been tested and theircondition recorded in the corresponding register spaces assigned tothem, the control then proceeds to block 40 where the price by countmode switch is tested. Under assumed conditions, this switch will beconditioned so that price by count is not the mode of operation,Consequently, control is then transferred to block 41.

Again, assuming this system is not operating in the auto price mode, azero will be stored in the auto price bit storage location in the statusregister 0001 and, as a result, the control of the program istransferred to block 48 of FIG. 2B via transfer B2. As a result, block48 tests the status register storage space 738 designated auto price inthe status register 0001. Assuming that the last cycle was not autoprice and that a zero bit is stored in this register indicating that thelast cycle was also a manual price entry, the control is transferredfrom block 48 to block 47. Block 47 determines whether or not the priceinput has changed.

Thus, block 47 compares the information just recorded in the storagespaces SW-.OP through SW-.PO with the previous price output registeredin the output price register 739 in the register 0011. Under the assumedconditions, the prices may or may not be the same. If the manualswitches are all set on zero, then these prices will be the same and theprice will not have changed so far as the control equipment isconcerned. As a result, the control goes to block 49 of FIG. 2B where asafety switch on the printer door is checked, since this will be closed,control then goes to block 50 where the condition of an auto zeroinhibit switch is tested. If these switch is operated, it is desirableto disable to the auto zero correction operations as described herein.

Assuming that the auto zero inhibiting switch is off, then the controlis transferred to block 53 over the transfer B8. Block 53 tests the autotare switch.

Under the assumed conditions, the information stored in the storagespace SW-.T in the storage register 0010 indicates that the AUTO-TAREswitch is not pushed with the result that the program now transfers toblock 144 via transfer I1 of FIG. 2I.

Block 144 causes the computer to test the storage areas SW-.T and SW-.OTand if none of the tare switches has been operated, the program istransferred to block 145 which causes the tare register area 720 of FIG.7 to be all returned to zero, or zeros again recorded in area under theassumed conditions. In addition, a one is recorded in the INTF statusregister space 736 of the status register 0010. Then the control istransferred to block 55 via B10 of FIG. 2B.

Block 55 causes the computer to compare the printer mode recorded inspace 722 of register 0010 with the recordings in the status registerbits 723 and 724. Since it is assumed herein that the printer mode willbe the manual mode, these registers will not have changed so theoperation will be transferred to block 57 via transfer B12. In block 57,the condition of the interlocked flag in the status bit register 736 isinterrogated and as pointed out above, this flag has been set to a oneso that control then goes to block 58 where the interlock flag ischanged from one to zero and the initialized flag INITF stored in space727 is set to a one. Next, the set bit in space 737 of the statusregister 0011 is set and the control transferred to block 66 via C5.Since this cycle of operations started from block 25, block 66 causesthe computer to transfer control back to block 25 via transfer A1.

Since the motion flag is not set, that is, since a zero is still storedin the status register storage space 718, the control will betransferred to block 81 via transfer E1. At this time, the block 81causes the computer to again test the T1F flag, that is, the T1F storagespace 717. During the previous cycle, as described above, a one wasstored in this block indicating that T1F is set. Consequently, at thistime the control will be transferred to block 86, instead of 82, asdescribed in the previous cycle. However, under the assumed conditions,the signal on the T1 clock lead is still zero so that control will benow transferred to block 84 via the transfer E4. Thereafter block 84tests the zero expand switch which, as assumed to be unoperated, so thatcontrol will then be transferred to block 39 via transfer A15.Thereafter the remainder of the second cycle is substantially the sameas described above assuming that none of the various keys or switcheshave been actuated.

At the end of the second cycle, control will be transferred to the block25 via A1 transfer in the manner described above and each succeedingcycle of the main program will be repeated in accordance with the abovedescription of the second cycle so long as the signal from theanalog-to-digital converter on the T1 clock lead remains zero. Duringeach of these cycles, the T1F or T1 flag signal is set in a one state bya one being stored in the storage space 717 and a zero signal remains onthe T1 clock lead from the analog-to-digital converter.

NO MOTION DETECTION

Assume now that during some one of the above-described cycles of themain program, the analog-to-digital converter 14 completes a conversionand supplies digital output signals to the control equipment 15.Consequently, the analog-to-digital converter 14 will also apply a onesignal to the T1 clock lead. As a result, when a control is transferredto the block 86 during the next main program cycle, as described above,the T1 lead will test one or true so that the control is now transferredto block 87 where the T1F or T1 flag is cleared. In other words, a zerois now stored in the T1F status register space 717 instead of a one.

Thereafter, the control goes to block 88 where the weight output signalsfrom the analog converter 14 are read into the raw weight register 710of FIG. 7.

FIG. 2J shows a flow chart of an exemplary sub-routine for enteringweight signals from the analog-to-digital converter in the raw weightregister 710 of FIG. 7.

As described above when the analog-to-digital converter is in conditionfor transferring digital signals to the raw weight register 710, anoutput signal is applied by the analog-to-digital converter to the T1lead. As a result the control sequence proceeds from block 86 throughblock 87 to block 88 as described above. Within block 88 the control istransferred to a block 370. This block indicates that the RO registerwithin the CPU unit is set to eleven. The P1 register is set to zero andthe R3 register also set to zero. These registers being located withinthe CPU unit.

The RO register is employed to indicate when all of the digits of theweight are transferred to the raw weight register 710. The P1 registeris employed to direct the digits to the proper register spaces withinthe raw weight register. The R3 register is employed to select thedesired decimal digit to be transferred from the analog-to-digitalconverter to the raw weight register 710. Thus initially with theseregisters set as described above, the block 371 to which the control istransferred from block 370 first reads the R3 register and finds a zerorecorded therein. Block 370 then translates this zero to indicate thatthe zero should be read from each one of the leads DIG SEL B, DIG SEL C,DIG SEL D and DIG SEL E. The translation order or sequence is designatedKBP which translates the binary digit in the R3 register into aone-out-of-four code. Next block 372 tests the digit select leads B, C,D and E and if any signal condition on these leads other than zero onall of them is found, the control is transferred back to transfer pointJ2 and the above cycle repeated. The small loop including blocks 371 and372 are then repeated until zero is found on all four of the digitselect leads DIG SEL B, DIG SEL C, DIG SEL D and DIG SEL E.

When a zero is found on all of these leads, the control is thentransferred to the block 373 where the value of this digit is read intothe raw weight register area selected by the P1 register in the CPUunit. This will be the first digit space in the raw weight register 710since a zero was previously set in the P1 register in the CPU unit.

After the first digit is thus transferred to the raw weight register710, the zero in the R3 register in the CPU unit is again translated bythe KBP operations into a one-out-of-four code and the signals on thedigit select conductors DIG SEL B, DIG SEL C, DIG SEL D and DIG SEL Ecompared with this code. If under the assumed conditions zeros are foundon all of these leads, thus corresponding to the zero in register R3after being translated to the one-out-of-four code, the control isadvanced to block 376.

If on the other hand the signals on the weight data conductors WT. DATA1, WT. DATA 2, WT. DATA 4 and WT. DATA 8 change during the time theweight is being read into the raw weight register 710, then when thesignals on the digit select leads DIG SEL B, DIG SEL C, DIG SEL D andDIG SEL E are again compared with the setting of the R3 register byblock 375 these signals will have changed so that the control is thentransferred back to transfer point J1 and thus to block 370 instead ofblock 376. Under these assumed conditions wherein the signals on the B,C, D and E digit select conductors change during the reading in of adigit, it is assumed that the digit transferred to the raw weightregister will be in error. Consequently, the transfer operations arestarted over again and proceed as described above. Namely, the controlwill be first transferred to block 370 where the registers RO, P1 and R3are set as described above. Then the control is advanced to block 371and the setting of the R3 register translated to a one-out-of-four codeand again compared with the B, C, D and E select conductors. This cycleis then repeated until the signals on these conductors are the same asthe translated setting of the R3 register at which time the digit on theweight data conductors 1, 2, 4 and 8 is again transferred to the rawweight register.

Assume that the signals on these digit select conductors do not changeso that when they are again tested by the block 375 they will againcorrespond to the translated setting of the R3 register. Consequently,the control is advanced to block 376 where the setting of these threeregisters P1, R3 and R0 are all incremented by one. The control thenadvances to block 377 where the number stored in the R0 register istested. Under the assumed conditions this number is now twelve (elevenplus one). Since this number is not zero, the control is transferred tothe J2 transfer point and thus to block 371 where the above cycles ofoperation are repeated until the second of the decimal digits of the rawweight are transferred from the analog-to-digital converter to the rawweight register. The control is then again transferred to block 376.Assuming that the signals on the B, C, D and E digit select conductorshave not been changed during the recording of the value of the seconddigit in accordance with block 376, the registers P1, R3 and R0 areagain incremented so that the next or number three digit will betransmitted from the interface equipment of FIG. 3A to the raw weightregister 710.

After the fifth digit has been thus selected and transferred to the rawweight register 710, the RO register in the CPU unit will have recordedin it fifteen. This is incremented by the sub-routine of block 376. As aresult, the setting of this R0 register will now be zero. Since this isa four digit binary register when the register is incremented withfifteen stored in it, it is restored to zero. With the result that thecontrol is now transferred from reading the weight to the block 89 ofFIG. 2E.

From block 88 the control sequence advances through blocks 96 and 97 andat times through block 97A which blocks are employed to advance the taretimer in a well-known manner. Briefly, the block 96 causes the countstored in the tare timer space 728 to be read out. Then block 97determines if the count read out is zero. If it is zero the controlsequence advances to block 89. If the count read out is not zero thenthe control sequence advances to block 97A where one is subtracted fromthe count read out and the new count restored in the tare timer storagespaces 728.

Next, in block 90, the computer determines whether or not there has beenmotion or a change in weight on the scale platform. The arrangement, inaccordance with the exemplary embodiment of this invention, is arrangedso that if the weight changes or is less than a predetermined amount,that is within a predetermined band, it is assumed that there is nomotion of the platform scale. If, on the other hand, a weight changeexceeds the predetermined band, then it is assumed that there is motionof a scale platform. In accordance with the present invention, thebandwidth may be predetermined to any desired value, which value isstored in the pre-assigned storage spaces in one of the ROM's.

Under the assumed conditions, zeros will be stored in the motion targetweight register 735. Assume now that the band is 0.003 pound, plus orminus, and that a weight of 0.004 pound is read into the raw weightregister 710 from the analog-to-digital converter 14 during this cycleof the control equipment 15. Then in accordance with block 90, the zeroweight from the motion target weight register 735 is subtracted from theweight in the raw weight register 710 and then the band 0.003 subtractedfrom the difference which leaves +0.001. Since the final difference ispositive, it indicates that motion is present. Next, the weight in thetarget weight register is subtracted from the weight in the raw weightregister and the band of 0.003 pound added to the difference, and sincethis sum is not negative, it does not indicate motion. However, motionwas indicated by the first calculation. Thereafter, in response to themotion indication from block 90, block 91 causes the program to transferto block 98 via the F1 transfer. Block 98 first clears the no motion orhit counter 726 (i.e. causes all zeros to be stored in this counterspace) and sets the motion flag MOTNF. That is, it causes a one to bestored in the status register 718. Then block 99 causes the weight inthe motion target weight register 735 to be changed to the 0.004 poundrecorded in the raw weight register. The weight of 0.004 pound remainsrecorded in the raw weight register 710 at this time. Next, an initialweight of 8 pounds representing the weight of the scale platter on theload cell is subtracted.

The program then proceeds through blocks 100 where zero expand switch istested and found not to be operated. At block 103 the zero range expandswitch is tested and found not to be operated, so the program then jumpsto block 105 via transfer F6 where the weight recorded in the raw weightregister 710 is corrected by the auto zero weight stored in the zerocorrection register 11, which is zero at this time under the assumedcondition. The program then proceeds to block 107 where the controlequipment determines that the weight on the platter is not greater than30 pounds. Consequently, the control then advances to block 109 where azero is recorded in the over capacity status register space 725.

Next, the control equipment 15 is advanced to the block 110 where themotion flag is tested. That is, the status register space 718 is readout and since a one is recorded in this space, the program then advancesto block 111 where the one recorded in the set status register space 737is tested. Since a one is assumed to be stored in this space, theprogram is then transferred to G7 so that the block 123 subtracts thetare weight in the register 720 from the weight in the raw weightregister 710, causes round off operation to be performed and restoresthe thus corrected weight in the raw weight register and moves the fourmost significant digits from the raw weight register 710 to the weightout register 712.

Next, the program advances through blocks 124 transfer G12, blocks 128and 129, 130 and 131 and transfer C5 to block 66.

Since this cycle of operation of the control equipment 15 started fromblock 25, as described above, the block 66 now causes the program to betransferred back over transfer A1 to block 25 and another cycle of thecontrol equipment 15 is initiated.

At this time the motion flag MOTNF is set, i.e. the status registerspace 718 has a one stored in it as described above, so the controlsequence advances to block 26 instead of being transferred to block 81via transfer E1.

In block 26, the status of the MOTNF status register space 718 is againtested and since a 1 is recorded in this space, this flag is not clear;consequently, the program is transferred by transfer E1 to block 81.

At this time the T1F flag is not set. In other words, a zero wasrecorded in the status register space 717 on the last cycle of thecontrol equipment 15. Consequently the program now proceeds to block 82where the condition of the T1 clock lead from the analog-to-digitalconverter is tested. At this time it is assumed that a 1 signal is onthis lead with the result that the program now transfers over the E4transfer to block 84. Since the zero expand switch is not operated, thiszero expand is not true with the result that the program is transferredover transfer A15 to block 39. The remainder of this cycle of thecontrol equipment 15 then is as described above through blocks 40, 41transfer B2 to blocks 48, 47, 49, 50, 52, 53 transfer I1 to block 144,then block 146 and transfer B10 to block 55. From block 55, control istransferred to block 57 over transfer B12 and then through block 57transfer C1 to block 62, transfer C5 to block 66.

Since this cycle was initiated through block 26, block 66 now returnsthe control to block 26 over transfer A2 and the above cycle ofoperation then repeated. This cycle of operation is then continuouslyrepeated so long as a 1 signal is applied to the T1 clock lead by theanalog-to-digital converter.

Next, when the analog-to-digital converter removes the 1 signal from theT1 clock lead, the program during the next cycle of the controlequipment 15 is subsequently transferred to blocks 81 and 82 in themanner described above, the T1 clock lead will not be true, in otherwords it will test 0 so the program is then advanced to block 83 wherethe T1 flag is again set; that is, the 1 is recorded in the T1F storagespace 717 in the status registers. Thereafter, the above cycles ofoperation of the control equipment will continue as described aboveinitially except that the block 66 of FIG. 2C will return the control toblock 26 over the A2 transfer since the cycle started from this blockinstead of block 25 as described initially.

By the use of the T1F flag and the testing of the T1 clock control leadas described above, the output from the analog-to-digital converter istransferred to the control equipment only once during each of the 200millisecond cycles of the analog-to-digital converter 14. This transferoccurs in the next succeeding cycle of the control equipment after the 1signal is applied to the T1 clock control lead. Thereafter the 1 signalhas to be removed fromt this lead and re-applied by theanalog-to-digital converter 14 before a subsequent weight will betransferred from the analog-to-digital converter to the controlequipment 15.

Since the control equipment 15 operates in the above-described mannerfor the various cycles, when weight information is not transferred fromthe analog-to-digital converter, the operation of the control equipment15 during such cycles will not be repeated. Instead the operation duringonly those cycles during which weight information is transmitted fromthe analog-to-digital converter to the control equipment 15 will bedescribed. However, it is to be understood that control equipment 15advances through numerous of these cycles in the manner described abovebetween each of these cycles during which weight information is read outfrom the analog-to-digital converter and stored in the raw weightregister 710.

Assume now on the next weighing cycle, that is the next time a weight isreceived from the analog-to-digital converter and stored in the rawweight register 710, the weight stored in this register will not havechanged but will be 0.004 pound. Consequently when the calculations atblock 90 have performed in the sequence as described above, thecalculations will indicate that no motion is present. No motion wouldalso be present if the weight received from the analog-to-digitalconverter does not vary more than 0.003 pound from the 0.004 poundpreviously received from the register.

Under these assumed conditions with the calculations performed inaccordance with block 90 indicating no motion, block 91 will then causethe control to be advanced to block 92 when the motion flag MOTNF isread out and checked. This time the motion flag will not be zero since a1 was previously stored in the status register space 718 and has notbeen changed. As a result, control is advanced to block 93 where the nomotion counter or hit counter 726 of FIG. 7 is incremented by one. Underthe assumed condition, 0 has been previously stored in this counter sothe counter will now indicate a count of 1. Control is then advanced toblock 94 where the count in this counter 726 is read out and since it isless than some predetermined value, the count will not be greater thanthis value with the result that the control is transferred via F2 toblock 99 and the remaining portion of the cycle repeated as describedabove.

On the next cycle during which weight indication is again received fromthe analog-to-digital converter in the manner described above, if nomotion is still determined by block 90, then the hit counter 726 willagain be incremented and have a count of 2. Thus each cycle during whichno motion is present, this counter is incremented by 1. If, however,during any of these cycles the calculations of block 90 indicate thatmotion is present, then block 91 will transfer the control to block 98via transfer F1 at which time the hit counter 726 is cleared, i.e. zerosare stored in the counter spaces, and the motion flag 718 is again setto 1; in other words, a 1 is written over the 1 already in this storageregister space.

After the predetermined number of no motion indications have beenobtained from calculations of block 90 and the control advanced throughblocks 91, 92, 93 to 94, it will be determined that the counter is inexcess of the required number of counts.

Thus, to obtain a no motion indication, it is not only necessary thatthe scale remain within a fixed band indication of weights, but alsothat it remain in this band for a predetermined interval of time. Thisinterval of time can be predetermined within increments of 0.200 of asecond, the cycle period of an analog-to-digital converter. Assumingthat five such increments are required thus requiring that the weightindication remain within 0.003 pound for one second when the control istransferred to block 94 and a count of five stored in the counter 726,block 94 will advance control to block 95 where the motion flag MOTNF iscleared. In other words, a 0 is now recorded in status register space718.

Thereafter the control is transferred to block 99 via transfer F2 andthen advanced through the blocks 99, 100, 103, transfer F6 to block 105,block 107, block 109 and to block 110.

In block 110, the motion flag is again tested and since a 0 is nowstored in the status register 718, the control is transferred to block115 over the transfer G1 and thereafter the control is transferred asdescribed hereinafter under the heading of "Automatic Zero Correction."On the next cycle of the control equipment 15, after the no motion flagis cleared as described, control is returned to the block 26. Inaccordance with this block, motion flag is read out and tested and sinceit is clear, control is advanced to block 27 where it is determinedwhether the scale is arranged to operate in the demand mode orcontinuous mode. Under the assumed conditions, the scale is arranged tooperate in the manual mode and not in the demand or continuous mode sothat the control continues to a block 28. At the block 28, a check ismade to see if a "motion detector inhibit" switch is closed to disablethe motion detector portion of the apparatus 15. It is assumed that theswitch is not closed and the control continues to block 29. Block 29determines that a reweigh is not necessary at this time so control istransferred to block 30. In accordance with block 30, the controlequipment under the assumed conditions will determine that print data isnot stored so the control sequence advances to block 31. Block 31determines that the no tare key is not pressed so that control isadvanced to block 34. If the weight is greater than 0.1 pound then thecontrol is advanced to block 35 where the set status register space 737is tested. This space 737 is assumed to be true so that the control isthen transferred back to block 25 via transfer A1. If the weight asassumed is not greater than 0.1 pound then block 34 causes the controlto be transferred back to block 25 via transfer A1. In either case theabove-described cycle then repeats starting with block 25 for each ofthe various cycles described so long as the motion flag is not set; thatis so long as zero remains recorded in the status register 178.

If the weight is greater than 0.1 pound, the set is not true, the weightis not minus, and is not over the capacity of the scale, then thecontrol sequence advances through blocks 34, 35, 36 and 37 to block 38.Block 38 causes an output print pulse which causes the weight to beprinted. Then the sequence returns to block 25 via transfer A1.Thereafter, the above-described sequences are repeated.

AUTOMATIC ZERO CORRECTION

Assume now that either when the scale is first turned on or that afterthe previous object has been weighed and removed from the scale, thescale has not returned accurately to zero. Assume, for example, that thescale has returned to 00.0004. Also assume that zeros are entered in thezero correction register 711 and after the various operations referredto above, have been completed, 00.004 pound is entered in the raw weightregister 710. A 1 will be registered in the weight sign register 715 and1 in the zero correction sign register 714.

The one in the sign registers indicate that the sign of the weight orzero correction is plus and zeros entered in these registers represent anegative sign or weight indication. The manner in which the varioussigns are determined and entered into the respective registers will beapparent from the following description.

Thus, on the first cycle of the control equipment 15 after the previousweight has been removed from the scale and the scale returned to idlecondition or the power turned on, 00.004 will be entered into the rawweight register 710 and a 1 indicating a plus will be entered in theweight sign register space 715. Next during this same cycle of operationof the control unit 15, the weight in the zero correction register 711is subtracted (block 105 FIG. 2F) from the weight in the raw weightregister and the difference is then re-entered in the raw weightregister 710. Under these assumed conditions, zero will be subtractedfrom the 00.004 recorded in the raw weight register and the difference00.004 rerecorded in the raw weight register 710.

Next the automatic zero correction limit of 00.005 pound is subtracted(block 115 FIG. 2G) from the 00.004 pound in the raw weight register andsince the 00.004 pound is less, the weight indication of the scale iswithin the automatic zero correcting range so the control equipment willthen follow additional steps required to automatically correct the00.004 pound. Next the 00.004 pound in the raw weight register iscompared with the zero or 1/4 graduation range of 00.002 pound (block117 FIG. 2G).

Both this comparison and the previous comparison may be made in anydesired manner such as, for example, by means of threshold circuits ofany well known and suitable type. However, in accordance with thepresent invention, this comparison is made by the central processor unitCPU 186 of the microcomputer or control unit 15.

Briefly, a series of orders or instructions direct the centralprocessing unit 186 to predetermined locations in the ROM units wherethe limits of 00.005 and 00.002 are stored. These instructions directthe central processing unit 186 to obtain these limits and then subtractthem from the weight in the raw weight register. As a result, thecentral processing unit 186 causes the limit 00.002 obtained from thepredetermined address in the ROM to be subtracted from the 00.004 storedin the raw weight register 710. The result of this subtraction is 00.002which is a positive number thus indicating that the magnitude of theweight in the raw weight register is not equal to or less than 0.002pound. As a result, 12 will be entered in the zero count register 713(block 118, FIG. 2G).

Next, the reading of 12 in the zero count register 713 is read out bythe control equipment (block 120) and since this reading is less than16, the zero count register 713 does not return to zero, the count inthis register is incremented by one so that a 13 is now stored in thezero count register 713 (blocks 119 and 114, FIG. 2G).

Next, since the weight stored in the raw weight register is not 00.000(block 132, FIG. 2G) the weight recorded in the zero correction register711 is compared with the 0.6 pound limit for the operation of the zerocorrection (block 121, FIG. 2G). In performing this comparison, asabove, any suitable type of comparing or threshold circuits may beemployed, however, in the specific arrangement described herein, thecentral processing unit CPU 186 will obtain, under control of orders orinstructions stored in the ROM's 188-192, the 0.6 of a pound from apredetermined location in the read only memory and then subtract theweight in the zero correction register 711 from this value. If the valuein the zero correction register 711 is less than the 0.6 of a pound thezero correcting operation will continue. This limit of 0.6 pound andalso the other limits of 00.005 and 00.002 pound may be changed ordetermined by the value stored in the read only storage devices ROM's atthe predetermined locations employed for storing these values.

Since under the assumed conditions the 00.000 stored in the zerocorrection register is less than 0.6 pound the weight stored in the zerocorrection register 711 is augmented or changed by 00.001 pound (block122, FIG. 2G) and the sign in the zero correction sign register 714 ischanged to a plus.

Next a round-off operation is performed by adding 00.005 to the weightnow recorded in the raw weight register 710. As a result, the weight of00.009 is rerecorded in the raw weight register 710 (block 123, FIG.2G).

Next the four most significant digits recorded in the raw weightregister 710 which are all zeros is transferred to the output weightregister 712 so that they will be available for controlling the outputindication of 00.00.

During a subsequent portion of this first cycle, the 13 stored in thezero count register 713 is again read out and since this number is not16, i.e. not 0, the 1/4 graduation lamp is turned off if it was on ormaintained off it was already off. Thereafter, during the remainingportion of this first cycle of the control unit 15, other operations maybe performed. However, the values stored in the various registersdescribed above will remain until the next operating cycle of thiscontrol unit 15.

During the next cycle of operation of the control unit 15, the 00.004weight will be registered again in a raw weight register 710 in the samemanner as during the first cycle. Then the value in the zero correctionregister 711 which is now 00.001 pound will be subtracted from theweight in the raw weight register 710 and the difference is rerecordedin the raw weight register 710. Thus 0.003 pound is now stored orrecorded in the raw weight register 710.

Next the 00.003 pound stored in the raw weight register 710 is comparedwith the 00.005 pound operating limit of the automatic zero correctingoperation which is obtained from the read only storage units of thesystem. Since the result of subtracting the 00.003 pound from the 00.005pound is positive, the plus sign remains stored in the zero correctionsign register and the system continues to perform additional operationsrequired for the automatic zero correction in accordance with thepresent invention.

Next the 00.003 pound stored in the raw weight register 710 is comparedwith the zero or 1/4 graduation range in the manner described above.Thus the 00.002 pound, obtained from the read only memory at thepredetermined location assigned to this limit, is subtracted from the0.003 pound in the raw weight register 710. The result of thissubtraction is a positive number, namely 00.001 pound.

Since the weight in the raw weight register is not less than 00.002pound the control unit causes 12 to be again entered in the zero countregister 713 and then this register read out as described above. Sincethe count is not 16, i.e. not 0, the count in the zero count register713is incremented by one so that 13 is now recorded in the zero countregister 713. In addition, since the weight in the raw weight transfer710 is not 00.000 the weight stored in the zero correction register 711of 00.001 pound, is compared with the limits of 0.6 pound of the zerocorrection range by subtracting the 00.001 from the 0.6 pound. Theresult is positive so the weight in the zero correction register 711 isaugmented by 00.001 pound.

As a result 00.002 pound is now recorded in the zero correction register711. Next, a roundoff operation is performed by adding 00.005 pound tothe 00.003 pound in the raw weight register 710 and the result 00.008pound recorded in the raw weight register 710.

Next the four most significant digits in the raw weight register, namely0000, are transferred to the output weight register so they will beavailable for controlling the display of 0000.

Also during this second cycle, the 13 recorded in the zero countregister is again read out as before and since the count is not 16, i.e.not 0, the 1/4 graduation lamp is maintained off.

During the remaining portion of this second cycle of the control unit 15the information recorded in the above registers employed in theautomatic zero correction operation remains substantially the same asdescribed.

Near the beginning of the third cycle of the operation of the controlunit 15, the raw weight 00.004 pound will again be registered in the rawweight register 710. Next the 00.002 pound stored in the zero correctionregister 711 will be subtracted from the raw weight 00.004 and thedifference 00.002 pound restored in the raw weight register 170.

Next the 00.002 pound weight in the raw weight register 710 is comparedwith the zero correcting limit of 00.005 pound. The 00.002 pound in theraw weight register 710 is subtracted from the 00.005 pound and sincethe result of this subtraction is 00.003 pound the plus sign remainsstored in the zero correction sign register 714 and the zero correctingoperation continues.

Next, the zero or 1/4 graduation range of 00.002 is subtracted from the00.002 pound in the raw weight register 710. The resulting difference of0 indicates that the weight in the raw weight register is equal to orless than the 00.002 pound recorded in the raw weight register 710.Consequently, the contents of the zero count register 713 is read outwhich is 13 as described above. Since this is less than 16 the zerocount register is incremented by 1 which causes 14 to be stored in thisregister at this time (blocks 117, 120, 119 and 114 in FIG. 2G). Sincethe weight recorded in the raw weight register 710 is not 00.000, theweight of 00.002 stored in the zero correction register is compared withthe 0.6 pound limit of the automatic correction range. The 00.002 issubtracted from the 0.6 pound and since the result is positive, 00.001is added to the 00.002 pound stored in the zero correction register 711and the sum 00.003 pound is now restored in the zero correction register711. Next the roundoff operation is performed by adding 00.005 to the00.002 in the raw weight register and the sum 00.007 now stored in theraw weight register 710. Next the four most significant digits of theweight recorded in the raw weight register is transferred to the outputweight register 712 where it is available for later controlling thedigital output indicator of the scale.

During this third cycle of operation the 14 now recorded in the zerocount register will again be read out and since it is less than 16, the1/4 graduation lamp will remain turned off. Thereafter during theremainder of the third cycle of operation of the control unit 15 afterthe scale has returned to zero or normal, the information recorded inthe various registers described above remains unchanged.

During the fourth cycle of operation of the control equipment 15 the rawweight of 00.004 is again stored in the raw weight register 710 and the00.003 now stored in the zero correction register 711 is subtracted fromthis 00.004 and the resulting difference 00.001 pound is now stored inthe raw weight register 710. This 00.001 pound is then compared with the00.005 limit of the automatic zero correction and also with the 00.002limit. As a result of both of these comparisons, the system works asdescribed above since the 00.001 stored in the raw weight register isless than 00.005 limit and also less than 00.002 limit.

Since the 00.001 weight stored in the raw weight register is less thanthe 00.002 limit, the number stored in the zero count register 713 willbe augmented by 1 so that 15 will now be stored in this register. Later,when this register is again read out, the 15 will be less than 16 so the1/4 graduation lamp will be maintained turned off.

Similarly, the 00.003 now stored in the zero correction register 711 iscompared with 0.6 limit of the zero correction range and as a result00.001 is added to the 00.003 in the zero correction register 711 andthe resulting 00.004 now stored in this register. Next the roundoffoperation is performed by adding 00.005 to the 00.001 in the raw weightregister and the resulting 00.006 sum now stored in the raw weightregister 710. Thereafter the four most significant digits 00.00 of theraw weight register 710 are moved to the weight output register 712where they are available for controlling the output display of thescale.

As before, during the remainder of this fourth cycle of operation of thecontrol unit 15 the information stored in the various registers employedin the zero correcting arrangement remain unchanged.

During the fifth cycle of operation of the control equipment 15 the rawweight of 00.004 pound is again stored in the raw weight register 710and the 00.004 now stored in zero correction register 711 subtractedfrom this 00.004. Resulting difference 00.000 is now stored in the rawweight register.

This weight is then compared with the 00.005 limit of the automatic zerocorrection range and also with the 00.002 limit.

As a result of both of these comparisons the system works substantiallyas described above. Briefly as a result of the comparison of the 00.000with the 00.002 limit, the 14 now stored in the zero count register 713is read out. Since this count is less than 16, the count is incrementedby one so that thereafter 15 is stored in the zero count register 713.At this time, since the weight in the raw weight register 710 is 00.000the weight stored in the zero correction register is not augmented butremains 00.004.

Thereafter, during the remaining portions of this fifth cycle ofoperation of the control unit 15, the system works substantially asdescribed. When the 15 stored in the zero count register 713 is read outit will cause the 1/4 graduation lamp to remain off because the count isless than 16.

During the next or sixth cycle of operation of the control unit 15 thesystem works substantially as described above except that when the zerocount register is incremented it will have stored in it a count of 16.Since this register stores four binary digits, the count of 16 willcause the register to return to zero. Later when this register is againread out during this cycle of operation the 16, or zeros, recorded inthe register will cause the 1/4 graduation lamp to be turned on whichindicates that the automatic zero correction has been made and that thescale is within 1/4 graduation of the least significant display digit.This time, as pointed out above, weight displayed on the scale will be00.00.

Thereafter during the succeeding cycles of operation of the controlequipment neither the zero correction register 711 nor the zero countregister 713 will be augmented; instead the contents of these registerswill be maintained substantially as described above until either aweight is placed on the scale or the zero drifts or wanders. If the zeroindication should drift or wander then it will be corrected in themanner described above.

Assume now that an object weighing one pound is placed on the scaleplatter or pan. As a result, the load cell together with its sensor andthe analog-to-digital converter will cause a new raw weight includingthe zero error to be entered in the raw weight register 170.

This new raw weight will be corrected by the weight of the pan orplatter as described above and as a result a weight of 01.004 will beentered in the raw weight register.

At this time, under the conditions assumed above, 00.004 is stillregistered in the zero correction register so this 00.004 is subtractedfrom the 01.004 in the raw weight register 710 and the difference 01.000is then stored in the raw weight register 710. Next the one poundweight, namely 01.000, stored in the raw weight register 710 is comparedwith the 00.005 pound limit of the automatic zero correcting range bysubtracting the 00.005 from the 01.000 pound. The result of thissubtraction is positive with the result that 13 is entered in the zerocount register 713, which later causes the 1/4 graduation lamp to beturned off. In addition, since the one pound is greater than 00.005there is no point in comparing the one pound with 00.002 limit so thatthe control unit 15 will immediately cause the roundoff operation byadding 0.005 to the weight recorded in the raw weight register and thuscause 00.005 to be added to the 01.000 weight and cause the sum 01.005to be stored in the raw weight register 710.

Next the four most significant digits, that is the 01.00 will betransferred to the output weight register 712 where they will controlthe output weight indication of the scale and thus accurately indicatethe one pound weight or object placed on the scale platter or pan. Solong as the 01.00 weight remains on the scale the above cycles ofoperation of the control unit 15 will be repeated. 00.004 remains storedin the zero correction register. 13 is repeatedly stored in the zerocount register with the result that the 1/4 graduation lamp remainsturned off and 01.00 is displayed. The raw weight of 01.004 obtainedfrom the scale is corrected by the 00.004 in the zero correctionregister so the correct weight 01.00 of the object on the scale iscorrectly displayed.

Assume now that after the object weighed above is removed from thescale, the scale now returns to -00.001 instead of to 00.004 pound. Thisweight -00.001 pound is entered in the raw weight register 710 after thescale has come to rest and the initial 8 pounds subtracted from thedigital output of the analog-to-digital converter as described hereinand a 0, indicating the minus sign, stored in the weight sign resister715.

Next, the plus 00.004 in the zero correction register 711 isalgebraically subtracted from -00.001 in the raw weight register, theresulting difference is -00.005 which is stored in the raw weightregister 710 and a minus sign or zero is stored in the weight signregister 715.

Next, the minus 00.005 recorded in the raw weight register 710 iscompared with the 00.005 automatic zero correction limits. At this timethe magnitude or absolute value of the weight in the raw weight registeris compared with the limits 00.005. Since it is equal to the lowerlimit, the automatic zero correcting sequence of operations will beperformed.

Next, the weight of -00.005 recorded in the raw weight register 710 iscompared with the 00.002 pound limit. Since this weight is greater inmagnitude than the limit, a 12 is now recorded in the zero countregister 713 and then this register read out. Since the count is lessthan 16, the count is incremented by 1 so that 13 is now recorded inthis register. As described above, the 13 in this register later causesthe zero or 1/4 graduation lamp to be turned off or maintained off if itis already off. Since the weight in the raw weight register 710 is notzero, the weight recorded in the zero correction register 711 issubtracted from the 0.6 pound limit and since the weight is less thanthe limit, 00.001 is subtracted from the weight in the zero correctionregister 711 so that 00.003 is now recorded in the zero correctionregister 711.

Next, the roundoff operation is performed by adding 00.005 to the weight-00.005 recorded in the raw weight register 710 and the sum 00.000rerecorded in the raw weight register. Next the four most significantdigits of this weight are transferred to the output register where theoutput indication will then be 0000 when the other operations requiredto display this number have been performed during the remaining part ofthis first cycle of control unit 15 after the scale has becomestabilized when the previous weight was removed from the pan or platter.

During the next cycle of the control unit 15, the -00.001 pound againwill be entered in the raw weight register 710 and a zero indicatingminus sign of the raw weight will be entered in the weight sign register715.

Next, the weight of 00.003 positive now recorded in the zero correctionregister is algebraically subtracted from the weight -00.001 in the rawweight register 710 and the resulting difference -00.004 is recorded inthe raw weight register 710.

Next, this weight in the raw weight register is compared with the 00.005pound which is the limit of the automatic zero correcting arrangementand since the absolute value of this weight is less than the limit, thesequence of operations of the automatic zero correction are continued.

Next, the weight of -00.004 pound is compared with the limit 00.002pound and since it is more than the limit, the 12 is again recorded inthe zero count register 713. The 12 is then read out of the register andsince it is less than 16, one is added to the 12, so 13 is now stored inthe register. Later the 13 causes the zero or 1/4 graduation lamp to beturned off or maintained off if it is already off, as under the assumedconditions.

The weight of 00.003 pound in the zero correction register is nowcompared with the 0.6 pound limit of the zero correcting arrangement andsince it is less, 00.001 is subtracted from the 00.003 weight recordedin the zero correcting register and the difference 00.002 rerecorded inthe zero correcting register.

Next, the roundoff operation is performed and 00.005 added to the weight-00.004 in the raw weight register and the sum -00.001 rerecorded in theraw weight register. Then the four most significant digits 00.00recorded in the output weight register so that they are available forcontrolling the output weight indication. At this time the minus sign isnot displayed.

During the next cycle of operation of the control unit 15 substantiallythe same operations are repeated except that when zero correctingregister 711 contents 00.002 is subtracted from the raw weight register-00.001, the resulting difference of -00.003 is recorded in the rawweight register 710 instead of -00.004. In addition 00.001 weight issubtracted from the 00.002 in the zero correction register so the weightof 00.001 will be recorded in the zero correction register 711 insteadof 00.002 as in the previous cycle of operation of the control unit 15.

During the next cycle of the control unit 15, the raw weight of -00.001pound again is entered in the raw weight register 710. Next the weightof 0.001 pound in the zero correcting register is algebraicallysubtracted from the -00.001 pound in the raw weight register 710 withthe result that -00.002 pound is restored in the raw weight register.The magnitude of this weight is first compared with the 00.005 limit ofthe automatic correcting range. Since its magnitude is less, the varioussteps of the automatic correction range are repeated. The magnitude ofthe weight of -00.002 pound in the raw weight register 710 is thencompared with the limit of 00.002 pound and since it is equal to thisvalue, the 13 now stored in the zero count register 713 is read out andsince this count is less than 16 it is increased by one leaving a 14 nowstored in this zero count register 173. This 14 is again later read outand employed to maintain the 1/4 graduation lamp off. Thereafter weightof 00.001 in the zero correcting register is compared with the 0.6 poundof the zero correcting range and since it is less, 00.001 pound issubtracted from the 00.001 pound in the zero correcting range registerand a difference 00.000 recorded in this same register. Thereafter theroundoff and transfer operations are performed as described above.

During the next cycle of operation of the control unit 15, substantiallythe same operations as described above are performed except that thezero correcting register 711 now has all zeros recorded in it so thatthe -00.001 remains recorded in the raw weight register. During thiscycle of operation, the zero count register 713 is read out and sincethe 14 recorded in this register is less than 16, one is added to thecontents of the register and the 15 again will be recorded in thisregister 713. This 15 is later read out and employed to maintain the 1/4graduation lamp turned off. In addition, 00.001 is subtracted from thezero correcting register leaving -00.001 stored in this register and aminus or zero stored in the zero sign correcting register.

During the next cycle of operation of the control unit 15, the 00.001minus stored in the zero correcting register will be algebraicallysubtracted from the -00.001 pound recorded in the raw weight register710 leaving all zeros recorded in the raw weight register. Consequently,no subtraction is made from the -00.001 pound recorded in the zerocorrection register. However, one is added to the zero count register.One is then added to the zero count register during each succeedingcycle of the control unit 15 until the predetermined number, which is16, i.e. all zeros, in an exemplary embodiment, is stored in thisregister. When the 16, or all zeros is later read out of the zero countregister, the control unit 15 will turn on the 1/4 graduation lamp.Thereafter the contents of the various registers remains substantiallyas described until another article is weighed on the scale. During thistime the display will correctly indicate 00.00. In addition, when thenext object is weighed the zero wander of -00.001 will be corrected sothe correct weight of the object will be displayed.

Assume now that for some reason after a given weighing operation theoutput from the scale, load cell, sensor and analog-to-digital converterreturns to 00.100 pound after the weight of 8 pounds has been subtractedas described above. Consequently, the weight of 00.100 pound will beentered in the raw weight register 710. In addition, a 1 representing aplus weight on the scale will be entered in the weight sign register715.

Next, the weight in the zero correction register 711, assuming thisweight to be 00.003 pound, will be subtracted from the weight in the rawweight register 710 and the difference 00.097 pound restored in the rawweight register. Next, the weight of 00.097 pound now recorded in theraw weight register 710 is compared with the automatic zero correctionlimit of 00.005 pound. Since the weight in the raw weight register 710is greater than 00.005 pound, the automatic zero correcting operationsare not performed and 13 is recorded in the zero count register, whichlater causes the 1/4 graduation lamp to be turned off, or maintained offit had previously been turned off.

Next, the weight in the raw weight register 710 is rounded off by adding00.005 pound to the 00.097 pound recorded in this register. The sum of00.102 pound is then rerecorded in the raw weight register and the fourmost significant digits 00.10 are entered in the output register 712where it is available for actuating the output indication of the scale.

The information recorded in the various registers then remainssubstantially as described for the remainder of this cycle of operationof the control unit 15.

During each of the succeeding cycles of the control unit 15, theoperations of the equipment relative to the raw weight register 710, theweight sign register 715, the zero correction register 711, the zerocorrection sign register 714 and the zero count register 713 and theweight output register 712 are substantially as described above.

However, the attendant or operator of the scale upon noting the 00.10weight indicated on the output of the scale will be informed that thescale is not in condition for another weighing operation. At this timethe operator may operate the zero expand range switch 176 to cause thescale to be corrected so that it will be in condition to accuratelyweigh the next object placed upon the pan or platter.

On the next cycle of operation of the control unit 15, after the zerocapture range expand switch 176 or button has been operated, the weightof 00.100 pound will be entered in the raw weight register 710. Inaddition, a 1 representing a plus sign is entered in the weight signresistor 715. Also at this time 00.003 is stored in the zero correctionregister 711 and a 1 indicating a plus sign is stored in the zerocorrection sign register 714.

With the zero capture range expand switch operated and the 00.100 poundentered in the raw weight register 710, the central processing unit 186will cause the weight entered in the raw weight register to be comparedwith 0.6 pound which is the assumed limit of the zero correction range.

Since under the assumed conditions the weight of 00.100 pound is lessthan 0.6 pound, the central processing unit 186 will cause a weight of00.100 pound in the raw weight register 710 to be transferred to thezero correction register 711. As a result 00.100 will now be stored inthe zero correction register 711 and then this weight is subtracted fromthe weight of the raw weight register 710 with the result that 00.000will now be stored in the raw weight register 710.

Next, the weight 00.000 in the raw weight register 710 is compared withthe automatic zero correcting range of 0.005 pound and since it is lessthan this limit, the zero correcting operation will be performed in themanner described above and the 00.00 indication transferred to theoutput weight register. Also, the 1/4 graduation lamp will be turned onas described above.

So long as the expand button or switch 176 is operated, the above cyclesof operation are repeated. When this button or switch is released, theweight stored in the zero correcting register 711 will correct theweight in the raw weight register 710 so that the corrected weight willbe within the 00.005 pound correcting limits. Consequently, theabove-described zero correcting operations are performed and the correctweight of an object, within the capacity of the scale, is correctlydisplayed.

Again, so long as the various factors affecting the zero indication ofthe scale do not vary more than 00.005 pound, the control arrangement 15operates as described above and maintains the scale zero indicationaccurately at zero so that the scale will accurately weigh variousobjects or commodities placed on its platter or pan. If the zero wandereffects exceed the 00.005 pound but do not exceed the 0.6 pound, thenthese effects can be corrected by the operator or attendant operatingthe zero capture range expand switch 176 and the scale is corrected asdescribed above.

The zero capture range expand switch 176 together with the zerocorrecting operation of the scale may be employed as a self-correctingtare arrangement so long as the weight of the container is less than 0.6pound and so long as variations from container to container, plus zerowander effects of the scale described above, do not exceed 00.005 pound.

Thus, assume that an empty container weighing 00.15 pound is placed onthe scale. The scale will indicate this weight of 00.15 pound accuratelyproviding, of course, the automatic zero correcting arrangement wasoperating satisfactorily and the 1/4 graduation lamp turned on prior toplacing the container on the platter or pan of the scale. The operatoror attendant will now operate the zero capture range expand switch 176which will correct for the weight of the empty container and cause thescale to indicate a zero output. The attendant may then fill thecontainer with a commodity and the scale will indicate accurately thecorrect weight of the commodity only and compute its cost if it is sodesired. Upon removing the filled container from the scale, the scalewill now indicate -00.15 pound, assumming no zero wander effects. If theattendant or operator now places another similar container on the scaleof the same weight as the previous container, then the scale indicationwill return to zero and the automatic zero correcting operationsperformed providing, of course, that the variation in weight of thecontainers plus the variation in any zero wander effects are less than0.005 pound. If, however, the variations are greater than 00.005 pound,the 1/4 graduation lamp will not light and the indication on the scalewill not return to zero. The attendant can then re-operate the zeroexpand range switch and cause the scale to automatically correctthereafter for automatic zero variations in the manner described herein.

If, of course, the weight of the container or variations in the weightof the container and the zero wander exceed the predetermined operatinglimits described above, then the operator or attendant can use the usualtare buttons or keys and operate the scale in accordance with prior artarrangements without employing the automatic zero correcting arrangementin accordance with the present invention.

As indicated above, the various limits of 00.002, 00.005 and 00.600 havebeen selected to illustrate the invention and may be changed as desiredfor various applications or uses of the scale.

ZERO EXPAND

It is desirable to frequently check the operation of the automatic zeroand the amount of correction that is being introduced by the automaticzero in the manner described above. To enable the amount of automaticzero correction being applied to be readily determined, a zero expandswitch 178 (FIG. 3) is provided. When this switch is operated, itprevents the operation of the automatic zero correction. In addition, onthe next cycle of the control equipment 15, if this cycle is not one inwhich weight is read out of the analog-to-digital converter and enteredinto the raw weight register 710, then when the program advances toblock 84, it will test this zero expand switch and, finding it operatedor true, control is then advanced to block 85 which sets the interlockflag INTF. In other words, it causes a 1 to be stored in the statusregister space 736. Later in this same cycle of operation of the controlequipment 15, the control is advanced to block 57 as described abovewith the result that the interlock flag is tested. That is, the 1 storedin the register space 736 is read out and since it is a 1, the controlis then advanced to block 58 which clears the interlock flag INTF byentering a zero in the register space 736 and, in addition, sets orenters a 1 in the initialize register space 727.

Thereafter, the control advances to block 59 at which a 1 is entered inthe storage space 737. The control then advances to block 66 over thetransfer C5. With these changes the above cycles of operation of thecontrol equipment 15 are then repeated until the cycle in which the rawweight is read out of the analog-to-digital converter and stored in theraw weight register 710. During this cycle the control is advanced toblock 100 in the manner described herein and since the zero expandswitch is now pressed or turned on, control is then advanced to block101 where the four least significant digits in the raw weight register710 are read out and moved to the weight out register 712 where theylater are caused to actuate the readout or display of the system whichwill then indicate the four least significant digits of the raw weightread into the raw weight register and thus indicate the amount ofcorrection being applied to the systemm by the automatic zero correctionarrangement.

When the zero expand switch 178 is restored to normal, it is thennecessary to initialize the system and to check the price per pound, thetare and finally to operate the lock switch 179 indicating that all thenecessary information is availiable for the next weighing operation.

TIMED TARE ENTRY

Each time the program is transferred to block 144 the control apparatustests the "no tare" switch 171 (FIG. 3) to determine whether or not thisswitch is operated. If the switch 171 is operated, then the program setsthe interlock flag INTF and transfers to block 145 which causes the tareregister 720 to be cleared or restored to zero and then the programadvances to block 55 via transfer B10 and the cycle of operation iscompleted as described above.

If the "no tare" switch 171 is not pushed or operated as previouslyassumed, then the control is advanced to block 146 where all of theother tare keys are tested to determine if any of them are operated. Ifnone are operated the sequence transfers to block 55 and the cyclecompleted as described above. If some one of these keys is operated, forexample the tare key 0.1 pound, then the control is advanced to block147 instead of to block 55 via transfer B10 as described above. Block147 determines whether or not 2.6 seconds has elapsed since another tarebutton was pushed. It is assumed that this is the first tare button tobe pushed, then 2.6 seconds will have elapsed since a previous tarebutton is pushed. Consequently, the tare timer spaces 728 will have allzeros stored in them so the program is advanced to block 148 where tareregister 720 is cleared or returned to zero. Thereafter the control isadvanced to block 149 where the 0.1 pound is entered in the tareregister 720 and the interlock flag is set by entering one in storagespace 736. Thereafter the program is advanced to block 55 via transferB10 and the cycle of operation in the manner described above.

In addition to entering the tare weight in the tare register space 720,the tare timer is set into operation as stated in block 149. This isaccomplished by entering 13 in this tare timer space 728. Then on eachof the cycles during which a weight is transferred from theanalog-to-digital converter to the raw weight register 710, one issubtracted from the number stored in the tare timer 728 as indicated inblocks 96, 97 and 97A as described above. After 13 of such cycles, 2.6seconds have elapsed.

If another one of the tare keys is operated in this 2.6 second period,then the control is tranferred from block 147 directly to block 149where the value of the second operated tare key is entered in the tarestorage spaces 720. Also, the tare timer is reset or recycled by againentering 13 in the tare timer storage spaces 728. Thus for example ifthe tare key 0.05 is actuated, then this figure will be entered in thetare register 720 with the result that the register now has entered init a tare weight of 0.15 pound. Thereafter the interlock andinitializing conditions must be checked and the lock switch 179 must beoperated in order to condition the system for weighing operationsinvolving subtracting tare weights as described herein.

If, however, the second key is operated 2.6 seconds after the previouskey then the next time the control sequence advances to block 147 in themanner described above, the sequence transfers to block 148 which clearsthe tare storage areas and then to block 149 so that the weightrepresented by only the last tare key operated is stored in the tarestorage areas 720.

OUTPUT CONTROL

When a package has been placed on the scale platter and weighed, and theweight corrected after a no motion condition has been established asdescribed herein, control will be transferred to block 26 via transferC5 to block 66 and then to block 26. The "MOTNF" flag is cleared at thistime so block 26 will transfer control to block 27. Block 27interrogates the printer mode switch 172 (FIG. 3) and branches aroundblock 28 to block 29 if the system is in either the demand or thecontinuous mode. Since we are assuming single mode, block 27 transferscontrol to block 28.

Block 28 interrogates the status storage space 729 status register 0001.This signal is true if, during the input operations a motion detectorinhibit switch in the printer is on. This switch is provided so thatsystems which are in vibratory installations (heavy machinery causingfloor vibrations or overhead fans, for example) can have the switchturned on to guarantee only one label per weight application. If theswitch is "on," control is tranferred to block 29.

Block 29 examines the status of a reweigh storage space 740 of statusregister 0001. A one or true of this reweigh signal is an indicationthat the previous printer operation was aborted due to a set-upmalfunction. If there was a malfunction, block 29 transfers control toblock 31 via A7 (this allows another print to be initiated for the samepackage to allow the printer to rectify the error). If there is noreweigh, block 29 tranfers control to block 30. Block 30 interrogatesthe status of storage space 730 of status register 0001. A true or onein this location indicates that a print has occurred and the printedlabel has not been removed. If this condition exists, block 30 tranferscontrol to block 25 via connector A1. Thus no print occurs during thismotion-no motion sequence. (Motion Detector Inhibit)

If a zero is stored in the print storage space in the status register0001, block 30 tranfers data to block 31 and, providing other condtionsare fulfilled, a label is printed.

Blocks 28 through 30 comprise a system whereby only one label per weightapplication is allowed, unless the printer malfunctions, in which case asubsequent motion-no motion cycle will be recognized.

If the motion detector inhibit switch is not on, block 28 transferscontrol to block 31 directly; thus allowing a new printer cycle for eachmotion-no motion detected.

Blocks 31 through 33 allow the printing of a label with the appliedweight being below a preselected minimum value (in this example, 0.10pound). The need of the minimum value inhibit is that if none werepresent, the system would be printing labels with zero weight on theplatter, an undesirable condition. The ability to print labels withapplied weights below the predetermined value is necessary for tests.

If the unit price is set to zero and the no tare key is depressed, anoutput print signal is generated when a motion - no motion cycle occurs,regardless of the applied weight. Block 31 interrogates the "no tare"switch 171 for a no tare signal. If this condition exists, control istransferred to block 32 which interrogates SW-.OP through SW-.PO (FIG.7). If the price is zero as indicated by SW-.OP through SW-.PO, allbeing zero, control is tranferred to block 33 which causes a 1 to bestored in the status storage space 731 of status register 0011 and theprinter will generate a label. Block 33 then transfers control to block25 via A1.

If either block 31 or block 32 are not true, control is tranferred toblock 34. Block 34 interrogates the output weight register 712 (FIG. 7).If the weight is less than 0.1 pound, control is returned to block 25via A1. If the net weight is greater than 0.1 pound, control istransferred to block 35.

Block 35 interrogates set bit space 737 in status register 0011. If setis true (an indication that interlocks are not satisfied) control isreturned to block 25 via A1. If set is false, control is transferred toblock 36.

In the weight processing description, the method of processing the rawweight information into net weight output information was described. Atthat time, it was shown that the value in the output weight register isthe magnitude only of the weight. Thus the weight could be greater than0.1 pound but be negative, in which case no print should occur. Block 36interrogates the weight sign storage space 715 in status register 0011of FIG. 7. If the signal is false (indicating a minus weight) control isreturned to block 25. If the signal is true, the system controltransfers to block 37.

Block 37 interrogates the level of the signal in storage space 725 instatus register 0011 (FIG. 7). If this signal is true (an indicationthat the applied weight exceeds the capacity of the weight converter)system control returns to blocks 25 via A1. If the scale weighingcapacity is not exceeded, control transfers to block 38.

Block 38 generates an output pulse similar to block 33. Control is thentransferred to block 25 via transfer A1.

As previously described, block 134 is activated by transfer from block130 via transfer H1. Block 134 interrogates the blank price signal fromthe printer into the input of ROM 191 (see FIG. 4A). If this signal isoff, block 134 bypasses block 135 and transfers control to block 136 viatransfer H3. If the signal is on, block 134 advances control to block135. Block 135 causes all bits of all words in the output price register739 (FIG. 7) to be changed to 1's (binary 15 causes blanks in theprinter). Control is then transferred to block 136.

Block 136 interrogates the blank weight from the printer into the inputof ROM 191 (see FIG. 4A). When this signal is off, control istransferred to block 139. When on, control is transferred to block 137.When the system is operated in the price by count mode, the normalfunction is to blank the weight field on the printed ticket. Thus, ablank weight off signal must cause the weight to be blanked and viceversa. The purpose of blocks 137 and 139 is to invert the sense of theblank weight switch when operating in price by count.

Thus, if block 136 enables block 137 and the system is in price bycount, block 138 is bypassed. If block 139 is activated instead, block138 is not bypassed. However, since this discussion is limited to beweight operation, a true in block 136 ultimately transfers control toblock 138. Block 138 causes all data in the output weight register 712to be forced to a 15 (blank) level. Control is then transferred to block140. A false in block 136 bypasses block 138 and transfers control toblock 140 through block 139 via connector H6.

Blocks 140 and 141 perform the same blanking function on the outputvalue register 741 (FIG. 7) bases on the level of the blank value signalinto the ROM 191 (FIG. 4A) and then transfers control to block 69 viatransfer D1.

Note that the blanking switches are located in the printer but this isfor convenience only; any location is acceptable.

Referring to FIG. 2D, the description of the service switch functionfollows. With a system as complex as this, it is desirable to providesome trouble isolation capabilities to improve the serviceability.

APPARATUS FOR ISOLATING ERRORS IN PRINTED RECORDS

Since the most probable failure will be incorrect price, weight or valuedata on the printed label, a series of servicemen controlled inputs areprovided. The most basic ones allow the serviceman to select which ofthese three fields (price, weight or total value) he wishes to havedisplayed in the weight display area. In this manner, he can determineif the fault is in the scale, as indicated by faulty output information,or if the fault is in the printer, as indicated by correct outputinformation by a faulty printed ticket.

In FIG. 5, it has been shown how the weight information is selected fromthe series of information being transmitted.

By supplying service switches whereby price or value information isplaced in the weight output register 712, the digital display can bemade to indicate price, weight or value as computed by the system andthus simplify fault isolation.

Referring to FIG. 2D, block 69 interrogates status register space 733 isstatus register 0001. During the input cycle, the condition of the priceinput to input 4 of data selector 199 (FIG. 4B) has been stored in thislocation. If block 69 determines that the display price signal is true,i.e. a one is stored in 733, control transfers to block 70 and thesignal contents of the output price register 739 are transferred to theoutput weight register 712 (FIG. 7). Thus the digital display willindicate price and if there is a discrepancy between the setting of theprice entry equipment and the displayed value, the servicemen canobserve this and proceed to determine the cause of the fault, havinglocalized it. Block 70 transfers control to block 73.

If block 69 determines that the display price signal is false, i.e. azero is stored in 733, control is transferred to block 71. Block 71interrogates status register space 734 of status register 0001 which hasbeen set up to coincide with the valve input to input 4 of data selector200 in FIG. 4B. If the display value is true, block 71 transfers controlto block 72. Block 72 transfers the contents of the output valueregister 741 into the output weight register 712 (FIG. 7) and thentransfers control to block 73. Thus the digital display indicates thecomputed value for fault isolation testing.

If block 71 senses that the display value signal is false, block 72 isbypassed and control is transferred to block 73 via transfer D3.

Block 73 transfers a signal to wire 273 of FIGS. 4A, 4B and 4C based onthe signals in word 0 of status registers 0000 to either illuminate orextinguish the zero limit indicator (FIG. 4C). Control is thentransferred to block 74. Block 74 updates the signals in the 4 × 16 bitRAM 228 of FIG. 4B (price, weight, value data and printer control) andalso updates the signals out of quad bistable latches 248 of FIG. 4C.Control then transfers to block 75.

Block 75 checks the multiplied result register 742 of FIG. 7 andtransfers control to block 76 if the answer obtained by multiplying theoutput price by the output weight is equal to or greater than $100.00.Block 76 trues space 732 in status register 0011. This signal is usedelsewhere to indicate an out of range condition by causing the outputvalue register 741 to be set to zero by means not shown. Other uses ofthis overvalue signal could be to illuminate a warning light and toprevent a print pulse. Block 76 transfers control to block 77.

If the computed value is less than $100.00, block 75 transfers controldirectly to block 77 via transfer D7, bypassing block 76.

Block 77 determines if the capacity of the analog-to-digital weightconverter 14 has been exceeded. If so, control is transferred to block78 which stores a one in status register space 725 in status register0011. This signal will be transferred to the quad bistable latch 248(FIG. 4C) to set output D to illuminate the out of range indicatorduring the next performance of block 74.

Block 78 then transfers control to block 66 via transfer C5. If theweight converter capacity is not exceeded, block 77 transfers control toblock 66 via connector C5. The system continues with the performance ofblock 66 and subsequent blocks as described previously.

Turning now to FIG. 5, the digital weight display 22 is shown in detail.The weight display 22 includes four sevensegment indicators 301-304. Theindicators are arranged in a row on a front panel on the apparatus 10with the indicator 301 displaying the hundredths or 0.0W pound weightdigit, the indicator 302 displaying the tenths or 0.W0 pound weightdigit, the indicator 303 displaying the units or W.00 pound weight digitand the indicator 304 displaying the tens or W0.00 pounds weight digit.The indicators 301-304 may be of any conventional sevensegment design,such as of a type using incandescent lamps or of a type using lightemitting diodes. Of course, other types of digital indicators may alsobe used. A multiplexing technique is used for sequentially supplyingdata to the four indicators 301-304. Only one of the four indicators isactually energized at any given instance. However, the indicators301-304 are energized at a sufficiently fast rate as to appear to becontinuously energized.

The printer data on the buses 232 from the RAM 228 is supplied through aBCD-to-seven-segment decoder 305 and seven buffer amplifiers 306 inparallel to each of the four indicators 301-304. The printer addressbuses 231 are used for supplying address data for scanning the fourweight display indicators 301-304. The address buses 231 are connectedto a 2-line to 4-line decoder 307. Two of the address buses 231determine which of the four indicators 301-304 is to energized as weightdata is received on the buses 232, while a third bus provides a strobesignal and a fourth of the buses provides an inhibit signal. The decoder307 has four outputs which pass through four buffer amplifiers 308 toenable inputs on the four weight indicators 301-304. The output from thedecoder 307 for energizing the units weight display 303 also applies asignal for energizing a decimal point on the units weight display 303.This output is applied through an inverter 309 to a buffer amplifiercomprising a transistor 310 and a bias resistor 311. The output from thetransistor 310 is connected through a resistor 312 to the decimal pointinput on the indicator 303. Thus, whenever the units indicator 303 isenabled, a decimal point is illuminated.

The apparatus 10 is designed for indicating weights ranging from -2pounds up to +30 pounds. In the event that the measured weight goesbelow zero, a minus sign is formed by illuminating the center element inthe tens indicator 304. This is accomplished by connecting the outputfrom the decoder 307 which enables the indicator 304 to a NAND 313. Theminus sign signal on the line 254 from the logic unit 15 is applied to asecond input on the gate 313. The output of the NAND gate is connectedthrough a NOR gate 314 and an inverter 315 to the input on the bufferamplifiers 306 which energizes the segment in the indicator 304 used toform the minus sign. The output from the BCD-to-seven-segment decoder305 which normally energizes this segment of the weight indicators301-304 is also connected through the NOR gate 314 to the bufferamplifiers 306. Thus, the middle segment in the other indicators 301-303and in the indicator 304 when a positive weight is read is energized bythe output of the decoder 305 passing through the gate 314 and theinverter 315 to the buffer amplifiers 306.

Although it is not normally exposed to an operator of the apparatus 10,a service switch 316 is shown with the weight display 22. The serviceswitch 316 is a normally open switch having a momentary price contact317 and momentary value contact 318. When the service switch 316 ismoved to a position wherein the price contact 317 is grounded, the linefour input to the eight-line to one-line decoder 199 (FIG. 4B) isgrounded. When this occurs, the strobe signal on the readout addressbuses 231 is changed to strobe the weight indicators 301-304 while pricedata is present on the printer data buses 232. Similarly, when theservice switch 316 is moved to ground the value contact 318, the linefour input of te eight-line to one-line decoder 200 (FIG. 4B) isgrounded. When this occurs, the strobe signal to the decoder 307 issynchronized with the computed value data on the printer data buses 232causing the indicators 301-304 to display the computed value. Aspreviously indicated, this permits maintenance personnel to isolate anerror in a printed label between the printer 21 and the logic unit 15.If the weight indicators 301-304 display a correct price per unit weightor a correct value for an article, then an error in the printed labelwill be isolated to the printer 21. However, if the indicators 301-304display the same error present on the printed label, then the error isisolated to either the logic unit 15 or to one of the data inputs to thelogic unit 15.

The printer 21 may be of any conventional design suitable for use withweighing and price computing apparatus. One typical printer design isshown in U.S. Pat. No. 3,163,247 which issued on Dec. 29, 1964 R. E.Bell et al. However, a preferred arrangement for the printer 21 is showndiagrammatically in the block diagram of FIG. 6. As previouslyindicated, the printer 21 includes apparatus for automatically enteringprice data into the logic unit 15. The auto-price apparatus includes anauto-price reader 325 which includes an optical reader for reading threedigits of price data from a commodity plate. The commodity plate alsoincludes raised type for printing on the labels the name of thecommodity. The three binary coded decimal price digits from theauto-price reader 325 are applied through a data selector 326 to thefour auto-price data lines 210-213 which are connected to the line oneinputs of the 8-line to 1-line decoders 198-201 of FIG. 4B. The dataselector 326 may also include apparatus such as exclusive OR gatesconnected for generating an auto-price parity bit on an output 224connected to the line six input to the decoder 200. An alternate andpreferred method for producing an auto-price parity bit is to store theparity information directly on the commodity plate for reading by theauto-price reader 325. The actual auto-price digit supplied from thereader 325 through the data selector 326 to the lines 210-213 isdetermined by signals on two auto-price address selection lines 327 and328 (from FIG. 4C). Signals on the address selection lines 327 and 328are received from the address buses 206 from the ROM 190 in the controlunit 15. Thus, when a commodity plate is inserted within the auto-pricereader 325, the address selector 326 applies one digit at a time of theprice per pound data on the lines 210-213 depending upon an addressselection signal received on the lines 327 and 328.

The three digits of the price per unit weight for an article beinglabeled, the four weight digits and the four value digits are printed onthe label by means of print wheels 329. Each of the print wheels 329 isconnected through a solenoid actuated clutch 330 to a common driveshaft. Outputs 240' from the printer data address amplifiers 240 (FIG.4B) are applied to a 4-line to 16-line decoder 331. Eleven of the outputlines from the decoder 331 are used for selecting the eleven clutchsolenoids 330 which selectively engage the eleven print wheels 329 withthe drive shaft. The outputs from the decoder 331 are connected throughsolenoid driver amplifiers 332 which power the clutch solenoids 330.Thus, when address data is received on the lines 240', one of thesolenoid clutches 330 is addressed for engaging the associated printwheel 329 with the drive shaft.

Each print wheel 329 is provided with a commutator 333 which rotateswith and indicates the position of the print wheel. The commutators 333are connected to four 16-line to 1-line decoders 334. The decoders 334have a BCD output corresponding to the digit to which an addressed printwheel is positioned. Address information is supplied to the decoders 334from the data address lines 240'. The BCD output from the decoders 334is applied to one input of a four bit comparator or coincidence circuit335. The printer data on the buses 232 from the RAM 228 (FIG. 4B) in thecontrol unit 15 is applied to a second input of the comparators 335.When an addressed print wheel 329 is driven to a desired number, theoutput of the decoders 334 will correspond to the printer data on thebuses 232 and the comparators 335 will apply a coincidence signal tocontrol logic 336. When coincidence occurs, power is removed from theenergized clutch solenoid 330.

The printer data on the buses 232 is also applied to a parity generator337 which generates a parity bit in a conventional manner, such as withthree exclusive OR gates. The parity bit from the generator 37 isapplied to a comparator 338, which may also be an exclusive OR gate,where it is compared with the printer data parity bit from the printerdata parity generator comprising the exclusive OR gates 233-235 (FIG.4B) in the control unit 15. If there is no parity check, the controllogic 336 applies a REWEIGH signal on the line 265 for recycling thecontrol unit 15. The control logic 336 also includes various switchesand mechanical sensors as well as inputs from and outputs to the controlunit 15. The printer clock input is obtained from the inverter 244 andthe SET input on line 263 from an inverter 262. Outputs from the controllogic 336 include the REWEIGH line 265, the take label line 267, theprint stored line 260, the add labels line 269, a motion detectorinhibit line connected to the line five input to the decoder 198 in thecontrol unit 15, the door open interlock connected to the line fourinput to the decoder 201, a printer readout on/off output connected tothe NAND gate 250 (FIG. 4C) and the blank weight, blank value and blankprice signals to the ROM 191. The manner in which these outputs aregenerated is known in the art and will not be covered in further detail.

The above-described features of the exemplary embodiment permit theapparatus 10 to weigh articles, compute an article value and print anarticle label with a speed and accuracy heretofore not possible.Furthermore, the accuracy of the apparatus 10 is maintained over a longperiod of time, despite changes in component parameters caused by ageingand changes in temperature.

In the exemplary embodiment of the apparatus 10 described above, weightmeasurements were in pounds and value was computed in dollars. It willbe appreciated by those of ordinary skill in the art that the apparatus10 may be readily adapted for other weight units, such as kilograms, andto other monetary units. The number of weight, price per unit weight andcomputed value digits also may be changed to meet any requirements forthe apparatus 10. Also, changes may be readily made in the degree orband of motion to which the motion detector is responsive and in theoperating range and increments of the automatic zeroing circuit.

The apparatus 10 has been described as generating a predetermined numberof significant weight digits, e.g., for significant weight digits forweights of from 0.01 pound up to 30.00 pounds. However, any other numberof digits may be generated and employed and any other weight and pricelimits employed as may be necessary or desirable. These weight digitsare displayed, printed on labels and used in computing values. Inaddition, at least one more least significant digit is generated for usein automatically and manually zeroing the apparatus 10 and in motiondetection. Although such additional least significant digit has beendescribed as a decimal, it will be apparent that it may be of otherfractional units such as one-third or one-fifth of the least significantone of the predetermined number of significant weight digits. If an oddfractional increment, such as one-third, is generated, then the scalezero will be centered and the automatic zero correction factor willgenerally not change except for compensating for any slow drift in thezero.

In describing the zero expansion circuitry, it has been stated that theadditional least significant weight digit is stored in the weight outputmemory during actuation of the zero expand switch 178 so that this digitwill appear on the weight display 22. In an alternative embodiment, aseparate indicator may be provided for displaying the additional leastsignificant weight digit. This indicator will normally be blanked andwill be energized only when the zero expand switch 178 is actuated. Itwill be appreciated that various other changes may also be made in theabove-described inventions without departing from the spirit and thescope of the following claims. ##SPC1## ##SPC2## ##SPC3## ##SPC4##

I claim:
 1. Weight measuring and indicating apparatus comprising, incombination, scale means for generating a digital weight signal having afirst predetermined number of digits, digital weight indicator means fordisplaying a second predetermined number of weight digits less than thefirst predetermined number of weight digits, said digital weightindicator means normally displaying the second predetermined number ofmost significant digits of the weight signal, and means for causing saiddigital weight indicator means to display the second predeterminednumber of least significant digits of the weight signal whereby the zeroaccuracy of the scale means is displayed when zero weight is one saidscale means.
 2. Weight measuring and indicating apparatus, as set forthin claim 1, wherein said scale means includes a load cell having anoutput proportional to a weight being measured, and wherein means isprovided for automatically correcting for error in the load cell output,and including means for inhibiting said error correcting means wheneversaid digital weight indicator means is displaying the least significantdigits of the weight signal.
 3. Weight measuring and indicatingapparatus comprising, in combination, scale means for generating adigital weight signal having a first predetermined number of digits,said scale means including means for maually adjusting the digitalweight signal to zero, digital weight means for normally displaying asecond predetermined number of weight digits less than the firstpredetermined number of weight digits, said digital weight indicatormeans normally displaying the most significant digits of the weightsignal, and means for causing said digital weight indicator means todisplay the least significant digits of the weight signal while saidscale means is adjusted to zero whereby said scale means is accuratelyadjusted while zero weight is on said scale means.
 4. Weight measuringand indicating apparatus, as set forth in claim 3, wherein said scalemeans includes a load cell having and output proportional to a weightbeing measured, and wherein means is provided for automaticallycorrecting for error in the load cell output, and including means forinhibiting said error correcting means whenever said digital weightindicator means is displaying the least significant digits of the weightsignal.
 5. Measuring apparatus comprising, in combination, scale meansfor generating a digital weight signal having a first predeterminednumber of digits corresponding to the weight of an article, said scalemeans including means for manually adjusting the digital weight signalto zero, digital weight indicator means for displaying a secondpredetermined number of weight digits less than the first predeterminednumber of weight digits, said digital weight indicator means normallydisplaying the second predetermined number of the most significantdigits of the weight signal, means for causing said digital weightindicator means to display the second predetermined number of the leastsignificant digits of the weight signal while said scale means isadjusted to zero whereby the zero accuracy of the scale means isdisplayed for accurate adjustment while zero weight is on said scalemeans, means for computing an article value from the secondpredetermined number of the most significant digits of the weight signaland a preselected price per unit weight, and means for printing anarticle label including the second predetermined number of the mostsignificant digits of the weight signal and the computed value. 6.Weight measuring and indicating apparatus comprising, in combination,scale means for generating a digital weight signal having a firstpredetermined number of digits, digital weight indicator means fordisplaying a second predetermined number of digital weight signals lessthan the first predetermined number of digital weight signals, saiddigital weight indicator means normally displaying the secondpredetermined number of the most significant digits of the digitalweight signal for each weight measurement, and means for displaying anumber of digital weight signals including a digital weight signalrepresenting a fraction of the least significant digit of the digitalweight signals normally displayed for each weight measurement toindicate the accuracy of the adjustments of the scale means to afraction of the least significant digit normally displayed for eachweight measurement.
 7. Weight measuring and indicating apparatuscomprising, in combination, scale means for generating a firstpredetermined number of digital place weight signals, digital weightindicator means for displaying a second predetermined number of digitalplace weight signals less than the first predetermined number of digitalplace weight signals, switching means, control means responsive to saidswitching means and interconnected with said scale means and with saiddigital weight indicator means, said control means comprising means for1 normally displaying by said digital weight indicator means the secondpredetermined number of the most significant digits of the digital placeweight signal for each weight measurement, and for (2) displaying bysaid digital weight indicator means a number of digital place weightsignals including a digital place weight signal representing a fractionof the least significant digital place of the digital place weightsignals normally displayed for each weight measurement to indicate theaccuracy of the adjustments of the scale means to a fraction of theleast significant digit of the normally displayed digital place weightsignals.
 8. An improved measuring apparatus comprising, in combination,programmed control means including a memory, scale means for generatinga digital weight signal having a predetermined number of digitscorresponding to the weight of an article, said programmed control meanscomprising for entering a digital weight signal into said memory, weightindicating means responsive to said programmed control means fordisplaying from said memory either a predetermined number of the mostsignificant weight digits less than said predetermined number of weightdigits or for displaying from said memory a predetermined number of theleast significant digits less than said predetermined number of weightdigits, and switching means having first and second positions, saidprogrammed control means also comprising means responsive to saidswitching means for causing said weight indicating means to display saidpredetermined number of most significant weight digits from said memorywhen said switching means is in its first position and for causing saidweight indicating means to display said predetermined number of leastsignificant digits from said memory when said switching means is in itssecond position.